fix(warning): taking the absolute value of 'bfloat16' has no effect

The compinv function is invalid when building for BFLOAT16 and leads to the following warning:
`taking the absolute value of unsigned type 'bfloat16' (aka 'unsigned short') has no effect`.
Update pre-processor conditions to remove its definition when building for BFLOAT16.

Author: mayeut

common.h

@@ -781,7 +781,7 @@ static __inline int readenv_atoi(char *env) {
 #endif
 #endif
 
-#if !defined(XDOUBLE) || !defined(QUAD_PRECISION)
+#if !defined(BFLOAT16) && (!defined(XDOUBLE) || !defined(QUAD_PRECISION))
 
 static __inline void compinv(FLOAT *b, FLOAT ar, FLOAT ai){