swscale/x86/hscale_fast_bilinear_simd: add inline asm guards

Should fix MSVC build

Found-by: jamrial
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswscale/x86/hscale_fast_bilinear_simd.c

@@ -25,6 +25,7 @@
 #define RET 0xC3 // near return opcode for x86
 #define PREFETCH "prefetchnta"
 
+#if HAVE_INLINE_ASM
 av_cold int ff_init_hscaler_mmxext(int dstW, int xInc, uint8_t *filterCode,
                                        int16_t *filter, int32_t *filterPos,
                                        int numSplits)
@@ -370,3 +371,4 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
         dst2[i] = src2[srcW-1]*128;
     }
 }
+#endif //HAVE_INLINE_ASM