Merge commit 'f637046d'

* commit 'f637046d':
  libavutil: Always use some GCC style attributes on clang
Merged-by: Clément Bœsch <cboesch@gopro.com>

libavutil/attributes.h

@@ -121,8 +121,7 @@
 #endif
 #endif
 
-
-#if defined(__GNUC__)
+#if defined(__GNUC__) || defined(__clang__)
 #    define av_unused __attribute__((unused))
 #else
 #    define av_unused
@@ -133,7 +132,7 @@
  * away.  This is useful for variables accessed only from inline
  * assembler without the compiler being aware.
  */
-#if AV_GCC_VERSION_AT_LEAST(3,1)
+#if AV_GCC_VERSION_AT_LEAST(3,1) || defined(__clang__)
 #    define av_used __attribute__((used))
 #else
 #    define av_used

libavutil/mem.h

@@ -97,7 +97,7 @@
     #define DECLARE_ASM_CONST(n,t,v)                    \
         AV_PRAGMA(DATA_ALIGN(v,n))                      \
         static const t __attribute__((aligned(n))) v
-#elif defined(__GNUC__)
+#elif defined(__GNUC__) || defined(__clang__)
     #define DECLARE_ALIGNED(n,t,v)      t __attribute__ ((aligned (n))) v
     #define DECLARE_ASM_CONST(n,t,v)    static const t av_used __attribute__ ((aligned (n))) v
 #elif defined(_MSC_VER)