[crypto/asn1/x_bignum.c] Explicit test against NULL

As a fixup to https://github.com/openssl/openssl/pull/9779 to better
conform to the project code style guidelines, this commit amends the
original changeset to explicitly test against NULL, i.e. writing

```
if (p != NULL)
```

rather than

```
if (!p)
```

(This is a backport of https://github.com/openssl/openssl/pull/9881)

Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9882)

diff --git a/crypto/asn1/x_bignum.c b/crypto/asn1/x_bignum.c
index c644199c9f81e59ccbbf8516d38789dedc5e69d1..f2de3de4deef8e48a68a29da89348cba6adb174c 100644 (file)
--- a/crypto/asn1/x_bignum.c
+++ b/crypto/asn1/x_bignum.c
@@ -102,7 +102,7 @@ ASN1_ITEM_end(CBIGNUM)
 static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
 {
     *pval = (ASN1_VALUE *)BN_new();
-    if (*pval)
+    if (*pval != NULL)
         return 1;
     else
         return 0;
@@ -110,7 +110,7 @@ static int bn_new(ASN1_VALUE **pval, const ASN1_ITEM *it)
 
 static void bn_free(ASN1_VALUE **pval, const ASN1_ITEM *it)
 {
-    if (!*pval)
+    if (*pval == NULL)
         return;
     if (it->size & BN_SENSITIVE)
         BN_clear_free((BIGNUM *)*pval);
@@ -124,7 +124,7 @@ static int bn_i2c(ASN1_VALUE **pval, unsigned char *cont, int *putype,
 {
     BIGNUM *bn;
     int pad;
-    if (!*pval)
+    if (*pval == NULL)
         return -1;
     bn = (BIGNUM *)*pval;
     /* If MSB set in an octet we need a padding byte */