[PATCH GnuPG] build: Fix GNUPG_CHECK_ENDIAN to work with gcc 14

Before this fix, running configure on Solaris 11.4 x86 with gcc 14
claimed x86 systems were big endian, because the test failed to compile:

conftest.c:103:1: error: return type defaults to 'int' [-Wimplicit-int]
  103 | main () {
      | ^~~~
conftest.c: In function 'main':
conftest.c:111:15: error: implicit declaration of function 'exit'
 [-Wimplicit-function-declaration]
  111 |               exit (u.c[sizeof (long) - 1] == 1);
      |               ^~~~

Signed-off-by: Alan Coopersmith <[email protected]>
---
 acinclude.m4 | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/acinclude.m4 b/acinclude.m4
index 98a87f673..a63edbe28 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -84,7 +84,7 @@ AC_DEFUN([GNUPG_CHECK_ENDIAN],
          not big endian
         #endif]])], gnupg_cv_c_endian=big, gnupg_cv_c_endian=little)])
         if test "$gnupg_cv_c_endian" = unknown; then
-            AC_RUN_IFELSE([AC_LANG_SOURCE([[main () {
+            AC_RUN_IFELSE([AC_LANG_PROGRAM([[#include <stdlib.h>]],[[
               /* Are we little or big endian?  From Harbison&Steele.  */
               union
               {
@@ -93,7 +93,7 @@ AC_DEFUN([GNUPG_CHECK_ENDIAN],
               } u;
               u.l = 1;
               exit (u.c[sizeof (long) - 1] == 1);
-              }]])],
+              ]])],
               gnupg_cv_c_endian=little,
               gnupg_cv_c_endian=big,
               gnupg_cv_c_endian=$tmp_assumed_endian
-- 
2.45.2