Comment 2 for bug 1533101

reduced test case:

typedef __simd64_int16_t int16x4_t;
typedef __simd128_int32_t int32x4_t;
int32x4_t a;
int16x4_t b;
int16x4_t c;
void WebRtcSpl_DownsampleFastNeon() {
  __builtin_neon_vmlals_lanev4hi(a, b, c, 0);
}

$ gcc-5 -c -g -O2 -march=armv7-a -mtune=generic-armv7-a -mfloat-abi=hard -mthumb downsample_fast_neon.i
downsample_fast_neon.i:1:9: error: unknown type name '__simd64_int16_t'
 typedef __simd64_int16_t int16x4_t;
         ^
downsample_fast_neon.i:2:9: error: unknown type name '__simd128_int32_t'
 typedef __simd128_int32_t int32x4_t;
         ^
downsample_fast_neon.i: In function 'WebRtcSpl_DownsampleFastNeon':
downsample_fast_neon.i:7:3: warning: implicit declaration of function '__builtin_neon_vmlals_lanev4hi' [-Wimplicit-function-declaration]
   __builtin_neon_vmlals_lanev4hi(a, b, c, 0);
   ^