Use static INLINE in optical flow intrinsics

Change-Id: Ia7a1d783c13290d915f6c19275f6e56603440072

av1/common/x86/optflow_refine_sse4.c

diff --git a/av1/common/x86/optflow_refine_sse4.c b/av1/common/x86/optflow_refine_sse4.c
index 2fbd01f..88aeb96 100644
--- a/av1/common/x86/optflow_refine_sse4.c
+++ b/av1/common/x86/optflow_refine_sse4.c
@@ -536,15 +536,15 @@
 #endif  // OPFL_BICUBIC_GRAD
 }
 
-inline __m128i LoadLo8(const void *a) {
+static INLINE __m128i LoadLo8(const void *a) {
   return _mm_loadl_epi64((const __m128i *)a);
 }
 
-inline __m128i LoadAligned16(const void *a) {
+static INLINE __m128i LoadAligned16(const void *a) {
   return _mm_load_si128((const __m128i *)a);
 }
 
-inline __m128i LoadUnaligned16(const void *a) {
+static INLINE __m128i LoadUnaligned16(const void *a) {
   return _mm_loadu_si128((const __m128i *)a);
 }