Add a compat stdatomic.h implementation based on windows atomics

Adapted from the code by Rémi Denis-Courmont from VLC

This merges libav commit c2755864afadfbaa349e8d583665c86fe99fa90b.

Signed-off-by: Wan-Teh Chang <wtc@google.com>
Reviewed-by: wm4 <nfxjfg@googlemail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/configure b/configure
index 8cbe6f8c42..2a77be9a0c 100755
--- a/configure
+++ b/configure
@@ -6384,6 +6384,8 @@ done
 if disabled stdatomic_h; then
     if enabled atomics_gcc; then
         add_cppflags '-I\$(SRC_PATH)/compat/atomics/gcc'
+    elif enabled atomics_win32; then
+        add_cppflags '-I\$(SRC_PATH)/compat/atomics/win32'
     fi
 fi