revert "extern inline" usage

as it breaks ICC:
libavcodec/libavcodec.a(snowenc.o): In function `encode_q_branch':
/home/fate/x86_64-linux-gnu-icc-2011.4.191/src/libavcodec/snowenc.c:405: undefined reference to `ff_epzs_motion_search'
/home/fate/x86_64-linux-gnu-icc-2011.4.191/src/libavcodec/snowenc.c:414: undefined reference to `ff_get_mb_score'
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavutil/attributes.h

@@ -41,12 +41,8 @@
 #endif
 
 #ifndef av_extern_inline
-#if defined(__INTEL_COMPILER) ||  defined(__GNUC_STDC_INLINE__)
-#    define av_extern_inline extern inline
-#else
 #    define av_extern_inline inline
 #endif
-#endif
 
 #ifndef av_noreturn
 #if AV_GCC_VERSION_AT_LEAST(2,5)