x86: Don't declare a non-static function as inline

This fixes building with clang in msvc mode, which does support
gcc style inline assembly.

libavcodec/x86/xvididct_sse2.c

@@ -342,7 +342,7 @@ DECLARE_ASM_CONST(16, int32_t, walkenIdctRounders)[] = {
     "movdqa   %%xmm6, 4*16("dct")     \n\t" \
     "movdqa   "SREG2", 7*16("dct")    \n\t"
 
-inline void ff_xvid_idct_sse2(short *block)
+void ff_xvid_idct_sse2(short *block)
 {
     __asm__ volatile (
         "movq     "MANGLE (m127) ", %%mm0                              \n\t"