lavc/x86/vc1dsp_init: Fix compilation with --disable-yasm.

libavcodec/x86/vc1dsp_init.c

@@ -98,10 +98,10 @@ av_cold void ff_vc1dsp_init_x86(VC1DSPContext *dsp)
 {
     int cpu_flags = av_get_cpu_flags();
 
-    if (HAVE_6REGS && INLINE_MMX(cpu_flags))
+    if (HAVE_6REGS && INLINE_MMX(cpu_flags) && EXTERNAL_MMX(cpu_flags))
         ff_vc1dsp_init_mmx(dsp);
 
-    if (HAVE_6REGS && INLINE_MMXEXT(cpu_flags))
+    if (HAVE_6REGS && INLINE_MMXEXT(cpu_flags) && EXTERNAL_MMXEXT(cpu_flags))
         ff_vc1dsp_init_mmxext(dsp);
 
 #define ASSIGN_LF(EXT) \