Description: Fix autoconf warning on missing AC_LANG_SOURCE

Author: Peter Blackman <peter@pblackman.plus.com>

Last-Update: 2020-07-09

Index: b/configure.ac

===================================================================

--- a/configure.ac

+++ b/configure.ac

@@ -36,9 +36,9 @@

 if test "${enable_atomic_ops}" = "yes" ; then

   AC_MSG_CHECKING([whether $CC knows 32-bit __sync_bool_compare_and_swap()])

-  AC_LANG_CONFTEST([#include <stdint.h>

+  AC_LANG_CONFTEST([AC_LANG_SOURCE[#include <stdint.h>

   int main() { uint32_t a = 4;

-  __sync_bool_compare_and_swap(&a, 4, 5); }])

+  __sync_bool_compare_and_swap(&a, 4, 5); }]])

   $CC conftest.c $CFLAGS -o conftest > /dev/null 2> /dev/null

   ret=$?

   rm -f conftest.o conftest

@@ -50,8 +50,8 @@

   fi

   AC_MSG_CHECKING([whether $CC knows 64-bit __sync_bool_compare_and_swap()])

-  AC_LANG_CONFTEST([#include <stdint.h>

-  int main() { uint64_t a = 4; __sync_bool_compare_and_swap(&a, 4, 5); }])

+  AC_LANG_CONFTEST([AC_LANG_SOURCE[#include <stdint.h>

+  int main() { uint64_t a = 4; __sync_bool_compare_and_swap(&a, 4, 5); }]])

   $CC conftest.c $CFLAGS -o conftest > /dev/null 2> /dev/null

   ret=$?

   rm -f conftest.o conftest