vendor: libsamplerate: only build SSE code on x86 platform

On non-x86 platforms, macro HAVE_IMMINTRIN_H (populated by CMake) will be zero.
But the original code use #ifdef for checking, which means a zero value will
trigger SSE optimizations. This is unexpected.

So I changed #ifdef to #if.

Author: AnClark

vendor/libsamplerate/src/common.h

@@ -172,7 +172,7 @@ SRC_STATE *zoh_state_new (int channels, SRC_ERROR *error) ;
 
 static inline int psf_lrintf (float x)
 {
-	#ifdef HAVE_IMMINTRIN_H
+	#if HAVE_IMMINTRIN_H
 		return _mm_cvtss_si32 (_mm_load_ss (&x)) ;
 	#else
 		return lrintf (x) ;
@@ -181,7 +181,7 @@ static inline int psf_lrintf (float x)
 
 static inline int psf_lrint (double x)
 {
-	#ifdef HAVE_IMMINTRIN_H
+	#if HAVE_IMMINTRIN_H
 		return _mm_cvtsd_si32 (_mm_load_sd (&x)) ;
 	#else
 		return lrint (x) ;