utils: Add ast_assert_return

Similar to pjproject's PJ_ASSERT_RETURN macro, this one will do the
following...

If the assert passes... NoOp

If the assert fails and AST_DEVMODE is defined, execute ast_assert()
then, if DO_CRASH isn't set, return from the calling function with
the supplied value.

If the assert fails and AST_DEVMODE is not defined, return from the
calling function with the supplied value.

The macro will execute a return without a value if one isn't suppled.

Change-Id: I0003844affeab550d5ff5bca7aa7cf8a559b873e

include/asterisk/utils.h

@@ -859,6 +859,13 @@ void DO_CRASH_NORETURN __ast_assert_failed(int condition, const char *condition_
 
 #ifdef AST_DEVMODE
 #define ast_assert(a) _ast_assert(a, # a, __FILE__, __LINE__, __PRETTY_FUNCTION__)
+#define ast_assert_return(a, ...) \
+({ \
+	if (__builtin_expect(!(a), 1)) { \
+		_ast_assert(0, # a, __FILE__, __LINE__, __PRETTY_FUNCTION__); \
+		return __VA_ARGS__; \
+	}\
+})
 static void force_inline _ast_assert(int condition, const char *condition_str, const char *file, int line, const char *function)
 {
 	if (__builtin_expect(!condition, 1)) {
@@ -867,6 +874,12 @@ static void force_inline _ast_assert(int condition, const char *condition_str, c
 }
 #else
 #define ast_assert(a)
+#define ast_assert_return(a, ...) \
+({ \
+	if (__builtin_expect(!(a), 1)) { \
+		return __VA_ARGS__; \
+	}\
+})
 #endif
 
 /*!