[FFmpeg-cvslog] configure: link to libatomic when it's present

[Anton Khirnov]

ffmpeg | branch: release/4.4 | Anton Khirnov <anton at khirnov.net> | Wed Jan 19 12:50:41 2022 +0100| [78062c6d71324fa89708211213b4267d2a57b806] | committer: Michael Niedermayer

configure: link to libatomic when it's present

C11 atomics in some configurations (e.g. 64bit operations on ppc64 with
GCC) require linking to libatomic.

Fixes #9275

(cherry picked from commit 2f0a214a6202516b4dda2bb22b6b3ac20e465d6d)
Signed-off-by: Anton Khirnov <anton at khirnov.net>
This is needed for MIPS build here
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=78062c6d71324fa89708211213b4267d2a57b806
---

 configure | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/configure b/configure
index 96fe27c549..89af70d72f 100755
--- a/configure
+++ b/configure
@@ -3706,23 +3706,23 @@ cws2fws_extralibs="zlib_extralibs"
 
 # libraries, in any order
 avcodec_deps="avutil"
-avcodec_suggest="libm"
+avcodec_suggest="libm stdatomic"
 avcodec_select="null_bsf"
 avdevice_deps="avformat avcodec avutil"
-avdevice_suggest="libm"
+avdevice_suggest="libm stdatomic"
 avfilter_deps="avutil"
-avfilter_suggest="libm"
+avfilter_suggest="libm stdatomic"
 avformat_deps="avcodec avutil"
-avformat_suggest="libm network zlib"
+avformat_suggest="libm network zlib stdatomic"
 avresample_deps="avutil"
 avresample_suggest="libm"
-avutil_suggest="clock_gettime ffnvcodec libm libdrm libmfx opencl user32 vaapi vulkan videotoolbox corefoundation corevideo coremedia bcrypt"
+avutil_suggest="clock_gettime ffnvcodec libm libdrm libmfx opencl user32 vaapi vulkan videotoolbox corefoundation corevideo coremedia bcrypt stdatomic"
 postproc_deps="avutil gpl"
-postproc_suggest="libm"
+postproc_suggest="libm stdatomic"
 swresample_deps="avutil"
-swresample_suggest="libm libsoxr"
+swresample_suggest="libm libsoxr stdatomic"
 swscale_deps="avutil"
-swscale_suggest="libm"
+swscale_suggest="libm stdatomic"
 
 avcodec_extralibs="pthreads_extralibs iconv_extralibs dxva2_extralibs"
 avfilter_extralibs="pthreads_extralibs"
@@ -6186,7 +6186,14 @@ check_headers asm/types.h
 # it seems there are versions of clang in some distros that try to use the
 # gcc headers, which explodes for stdatomic
 # so we also check that atomics actually work here
-check_builtin stdatomic stdatomic.h "atomic_int foo, bar = ATOMIC_VAR_INIT(-1); atomic_store(&foo, 0); foo += bar"
+#
+# some configurations also require linking to libatomic, so try
+# both with -latomic and without
+for LATOMIC in "-latomic" ""; do
+    check_builtin stdatomic stdatomic.h                                                 \
+        "atomic_int foo, bar = ATOMIC_VAR_INIT(-1); atomic_store(&foo, 0); foo += bar"  \
+        $LATOMIC && eval stdatomic_extralibs="\$LATOMIC" && break
+done
 
 check_lib advapi32 "windows.h"            RegCloseKey          -ladvapi32
 check_lib bcrypt   "windows.h bcrypt.h"   BCryptGenRandom      -lbcrypt &&