build: check for libatomic and __atomic operations

Add check in old-configure as well. Reformat the check to use a maximum of 80
columns in the wscript.
Signed-off-by: Stefano Pigozzi <stefano.pigozzi@gmail.com>

old-configure

@@ -1329,6 +1329,21 @@ if test "$_pthreads" = no ; then
   die "Unable to find pthreads support."
 fi
 
+
+echocheck "compiler support for __atomic built-ins"
+_atomic=no
+for _ld_tmp in "" "-latomic" ; do
+  statement_check stdint.h 'int64_t test = 0; test = __atomic_add_fetch(&test, 1, __ATOMIC_SEQ_CST)' $_ld_tmp &&
+    libs_mplayer="$libs_mplayer $_ld_tmp" && _atomic=yes && break
+done
+if test "$_atomic" = yes ; then
+  def_atomic="#define HAVE_ATOMIC_BUILTINS 1"
+else
+  def_atomic="#define HAVE_ATOMIC_BUILTINS 0"
+fi
+echores "$_atomic"
+
+
 if test "$_pthreads" = yes ; then
 
 # Cargo-cult for -lrt, which is needed on not so recent glibc version for
@@ -3521,6 +3536,7 @@ $def_avresample_has_set_channel_mapping
 
 $def_fast_64bit
 $def_pthreads
+$def_atomic
 
 #define HAVE_INLINE_ASM 1
 

wscript

@@ -98,6 +98,13 @@ main_dependencies = [
         'func': check_pthreads,
         'req': True,
         'fmsg': 'Unable to find pthreads support.'
+    }, {
+        'name': 'atomic_builtins',
+        'desc': 'compiler support for __atomic built-ins',
+        'func': check_libs(['atomic'],
+            check_statement('stdint.h',
+                'int64_t test = 0;'
+                'test = __atomic_add_fetch(&test, 1, __ATOMIC_SEQ_CST)'))
     }, {
         'name': 'librt',
         'desc': 'linking with -lrt',