include/compiler: drop likely/unlikely annotations

We have no more in-tree users of these. Besides, let's assume that the
CPU's branch predictor always has better clues than we might have when
assessing the likeliness of a condition.

Bonus: this clears a recurring source of namespace clashes with C++
frameworks like Boost.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

include/evl/compiler.h

@@ -24,11 +24,6 @@
 #define __stringify(x...)	__stringify_1(x)
 #endif
 
-#ifndef likely
-#define likely(x)	__builtin_expect(!!(x), 1)
-#define unlikely(x)	__builtin_expect(!!(x), 0)
-#endif
-
 #ifndef __noreturn
 #define __noreturn	__attribute__((__noreturn__))
 #endif