[libc] Add __builtin_expect tag on assert conditions; NFC

Author: goldsteinn

libc/src/__support/libc_assert.h

@@ -71,7 +71,7 @@ LIBC_INLINE void report_assertion_failure(const char *assertion,
 
 #define LIBC_ASSERT(COND)                                                      \
   do {                                                                         \
-    if (!(COND)) {                                                             \
+    if (LIBC_UNLIKELY(!(COND))) {                                              \
       LIBC_NAMESPACE::write_to_stderr(__FILE__ ":" __LIBC_LINE_STR__           \
                                                ": Assertion failed: '" #COND   \
                                                "' in function: '");            \

libc/src/assert/assert.h

@@ -19,7 +19,7 @@
 #define assert(e) (void)0
 #else
 #define assert(e)                                                              \
-  ((e) ? (void)0                                                               \
-       : LIBC_NAMESPACE::__assert_fail(#e, __FILE__, __LINE__,                 \
-                                       __PRETTY_FUNCTION__))
+  (LIBC_LIKELY(e) ? (void)0                                                    \
+                  : LIBC_NAMESPACE::__assert_fail(#e, __FILE__, __LINE__,      \
+                                                  __PRETTY_FUNCTION__))
 #endif // NDEBUG