Port AC_C_BIGENDIAN to recent clang

Problem and trivial patch reported by Matthieu Gautier in:
https://lists.gnu.org/r/bug-autoconf/2019-05/msg00006.html
* lib/autoconf/c.m4 (AC_C_BIGENDIAN): Use unsigned short for
values greater than 2**15 - 1.

diff --git a/lib/autoconf/c.m4 b/lib/autoconf/c.m4
index 42c6ac1b1c29748ef7a9f9792301e3280b5be049..9096b5cc1801d4c25e939986e5b77d317400177e 100644 (file)
--- a/lib/autoconf/c.m4
+++ b/lib/autoconf/c.m4
@@ -1648,16 +1648,16 @@ AC_DEFUN([AC_C_BIGENDIAN],
        [# Try to guess by grepping values from an object file.
         AC_COMPILE_IFELSE(
           [AC_LANG_PROGRAM(
-             [[short int ascii_mm[] =
+             [[unsigned short int ascii_mm[] =
                  { 0x4249, 0x4765, 0x6E44, 0x6961, 0x6E53, 0x7953, 0 };
-               short int ascii_ii[] =
+               unsigned short int ascii_ii[] =
                  { 0x694C, 0x5454, 0x656C, 0x6E45, 0x6944, 0x6E61, 0 };
                int use_ascii (int i) {
                  return ascii_mm[i] + ascii_ii[i];
                }
-               short int ebcdic_ii[] =
+               unsigned short int ebcdic_ii[] =
                  { 0x89D3, 0xE3E3, 0x8593, 0x95C5, 0x89C4, 0x9581, 0 };
-               short int ebcdic_mm[] =
+               unsigned short int ebcdic_mm[] =
                  { 0xC2C9, 0xC785, 0x95C4, 0x8981, 0x95E2, 0xA8E2, 0 };
                int use_ebcdic (int i) {
                  return ebcdic_mm[i] + ebcdic_ii[i];