BLI_math: don't use asserts in inline API

Requires BLI_utildefines.h to be included first,
(already noted in other inline code).

Possible alternative could be to move BLI_assert into own header.

source/blender/blenlib/intern/math_bits_inline.c

@@ -33,7 +33,9 @@
 
 MINLINE int bitscan_forward_i(int a)
 {
+#if 0  /* No BLI_assert in INLINE :/ */
 	BLI_assert(a != 0);
+#endif
 #  ifdef _MSC_VER
 	unsigned long ctz;
 	_BitScanForward(&ctz, a);