Fix T55137: Compilation failing on non-x86-64 architectures

Some conversion helper functions were (most likely by accident) contained
inside an ifdef for SSE2 support, so on e.g. ARM they would be undefined
and therefore cause compilation to fail.

source/blender/blenlib/intern/math_base_inline.c

@@ -513,6 +513,8 @@ MALWAYS_INLINE __m128 _bli_math_blend_sse(const __m128 mask,
 	return _mm_or_ps(_mm_and_ps(mask, a), _mm_andnot_ps(mask, b));
 }
 
+#endif  /* __SSE2__ */
+
 /* Low level conversion functions */
 MINLINE unsigned char unit_float_to_uchar_clamp(float val)
 {
@@ -544,6 +546,4 @@ MINLINE unsigned char unit_ushort_to_uchar(unsigned short val)
 	(v1)[3] = unit_float_to_uchar_clamp((v2[3]));                                           \
 } ((void)0)
 
-#endif  /* __SSE2__ */
-
 #endif /* __MATH_BASE_INLINE_C__ */