Use macros instead of inline functions to replace the following missing C99

functions: exp2, exp2f, log2, log2f.

Should fix compilation in systems where these functions are defined in math.h
but not implemented.

Originally committed as revision 21231 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/internal.h

@@ -264,17 +264,13 @@ if ((y) < (x)) {\
 }
 
 #if !HAVE_EXP2
-static av_always_inline av_const double exp2(double x)
-{
-    return exp(x * 0.693147180559945);
-}
+#undef exp2
+#define exp2(x) exp((x) * 0.693147180559945)
 #endif /* HAVE_EXP2 */
 
 #if !HAVE_EXP2F
-static av_always_inline av_const float exp2f(float x)
-{
-    return exp2(x);
-}
+#undef exp2f
+#define exp2f(x) exp2(x)
 #endif /* HAVE_EXP2F */
 
 #if !HAVE_LLRINT
@@ -285,17 +281,13 @@ static av_always_inline av_const long long llrint(double x)
 #endif /* HAVE_LLRINT */
 
 #if !HAVE_LOG2
-static av_always_inline av_const double log2(double x)
-{
-    return log(x) * 1.44269504088896340736;
-}
+#undef log2
+#define log2(x) (log(x) * 1.44269504088896340736)
 #endif /* HAVE_LOG2 */
 
 #if !HAVE_LOG2F
-static av_always_inline av_const float log2f(float x)
-{
-    return log2(x);
-}
+#undef log2f
+#define log2f(x) log2(x)
 #endif /* HAVE_LOG2F */
 
 #if !HAVE_LRINT