sectransp: fix `HAVE_BUILTIN_AVAILABLE` checks to not emit warnings

`HAVE_BUILTIN_AVAILABLE` is a curl macro set via autotools and cmake.
Like other `HAVE_`s it signals availability if defined.

SecureTransport code was specifically looking for the value 1, which
triggered compiler warnings when the feature was not present.

Replace the existing workaround of locally suppressing the compiler
warning with using `defined()`.

autotools:
```
767 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
      |                                                    ^~~~~~~~~~~~~~~~~~~~~~
../../lib/vtls/sectransp.c: In function 'sectransp_connect_step1':
../../lib/vtls/sectransp.c:1140:52: error: "HAVE_BUILTIN_AVAILABLE" is not defined, evaluates to 0 [-Werror=undef]
 1140 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
      |                                                    ^~~~~~~~~~~~~~~~~~~~~~
../../lib/vtls/sectransp.c:1240:52: error: "HAVE_BUILTIN_AVAILABLE" is not defined, evaluates to 0 [-Werror=undef]
 1240 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
      |                                                    ^~~~~~~~~~~~~~~~~~~~~~
../../lib/vtls/sectransp.c: In function 'sectransp_connect_step2':
```
Ref: https://github.com/curl/curl/actions/runs/9815428701/job/27104448045#step:6:499

cmake gcc:
```
 1140 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
      |                                                    ^~~~~~~~~~~~~~~~~~~~~~
/Users/runner/work/curl/curl/lib/vtls/sectransp.c:1240:52: error: "HAVE_BUILTIN_AVAILABLE" is not defined, evaluates to 0 [-Werror=undef]
 1240 | #if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
      |                                                    ^~~~~~~~~~~~~~~~~~~~~~
/Users/runner/work/curl/curl/lib/vtls/sectransp.c: In function 'sectransp_connect_step2':
/Users/runner/work/curl/curl/lib/vtls/sectransp.c:2231:51: error: "HAVE_BUILTIN_AVAILABLE" is not defined, evaluates to 0 [-Werror=undef]
 2231 | #if(CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
      |                                                   ^~~~~~~~~~~~~~~~~~~~~~
```
Ref: https://github.com/curl/curl/actions/runs/9815428701/job/27104445425#step:8:355

Cherry-picked from #14097
Closes #14122

diff --git a/lib/vtls/sectransp.c b/lib/vtls/sectransp.c
index a9ed1bf2ab355f4515c29f44f281e3cc72fdd481..0866af04e4fd4562e8f398118d2559fb20ff316e 100644 (file)
--- a/lib/vtls/sectransp.c
+++ b/lib/vtls/sectransp.c
@@ -49,7 +49,6 @@
 #ifdef __GNUC__
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Waddress"
-#pragma GCC diagnostic ignored "-Wundef"
 #pragma GCC diagnostic ignored "-Wunreachable-code"
 #endif
 
@@ -735,13 +734,14 @@ static CURLcode sectransp_version_from_curl(SSLProtocol *darwinver,
       return CURLE_OK;
     case CURL_SSLVERSION_TLSv1_3:
       /* TLS 1.3 support first appeared in iOS 11 and macOS 10.13 */
-#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
+#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && \
+    defined(HAVE_BUILTIN_AVAILABLE)
       if(__builtin_available(macOS 10.13, iOS 11.0, *)) {
         *darwinver = kTLSProtocol13;
         return CURLE_OK;
       }
 #endif /* (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) &&
-          HAVE_BUILTIN_AVAILABLE == 1 */
+          defined(HAVE_BUILTIN_AVAILABLE) */
       break;
   }
   return CURLE_SSL_CONNECT_ERROR;
@@ -764,7 +764,8 @@ static CURLcode set_ssl_version_min_max(struct Curl_cfilter *cf,
   /* macOS 10.5-10.7 supported TLS 1.0 only.
      macOS 10.8 and later, and iOS 5 and later, added TLS 1.1 and 1.2.
      macOS 10.13 and later, and iOS 11 and later, added TLS 1.3. */
-#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
+#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && \
+    defined(HAVE_BUILTIN_AVAILABLE)
   if(__builtin_available(macOS 10.13, iOS 11.0, *)) {
     max_supported_version_by_os = CURL_SSLVERSION_MAX_TLSv1_3;
   }
@@ -774,7 +775,7 @@ static CURLcode set_ssl_version_min_max(struct Curl_cfilter *cf,
 #else
   max_supported_version_by_os = CURL_SSLVERSION_MAX_TLSv1_2;
 #endif /* (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) &&
-          HAVE_BUILTIN_AVAILABLE == 1 */
+          defined(HAVE_BUILTIN_AVAILABLE) */
 
   switch(ssl_version) {
     case CURL_SSLVERSION_DEFAULT:
@@ -1137,7 +1138,8 @@ static CURLcode sectransp_connect_step1(struct Curl_cfilter *cf,
     switch(conn_config->version) {
     case CURL_SSLVERSION_TLSv1:
       (void)SSLSetProtocolVersionMin(backend->ssl_ctx, kTLSProtocol1);
-#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
+#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && \
+    defined(HAVE_BUILTIN_AVAILABLE)
       if(__builtin_available(macOS 10.13, iOS 11.0, *)) {
         (void)SSLSetProtocolVersionMax(backend->ssl_ctx, kTLSProtocol13);
       }
@@ -1147,7 +1149,7 @@ static CURLcode sectransp_connect_step1(struct Curl_cfilter *cf,
 #else
       (void)SSLSetProtocolVersionMax(backend->ssl_ctx, kTLSProtocol12);
 #endif /* (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) &&
-          HAVE_BUILTIN_AVAILABLE == 1 */
+          defined(HAVE_BUILTIN_AVAILABLE) */
       break;
     case CURL_SSLVERSION_DEFAULT:
     case CURL_SSLVERSION_TLSv1_0:
@@ -1237,7 +1239,8 @@ static CURLcode sectransp_connect_step1(struct Curl_cfilter *cf,
   }
 #endif /* CURL_BUILD_MAC_10_8 || CURL_BUILD_IOS */
 
-#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
+#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && \
+    defined(HAVE_BUILTIN_AVAILABLE)
   if(connssl->alpn) {
     if(__builtin_available(macOS 10.13.4, iOS 11, tvOS 11, *)) {
       struct alpn_proto_buf proto;
@@ -2228,7 +2231,8 @@ check_handshake:
         break;
     }
 
-#if(CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && HAVE_BUILTIN_AVAILABLE == 1
+#if (CURL_BUILD_MAC_10_13 || CURL_BUILD_IOS_11) && \
+    defined(HAVE_BUILTIN_AVAILABLE)
     if(connssl->alpn) {
       if(__builtin_available(macOS 10.13.4, iOS 11, tvOS 11, *)) {
         CFArrayRef alpnArr = NULL;