Include/enable assert.h/assert() when it is available

CODING_STANDARDS

@@ -64,6 +64,9 @@ Exceptions:
     not recommended. Since most of PHP_* macros are ZEND_* macro alias, use of
     PHP_* macro makes browsing source with tag search harder.
 
+[8] Use assert(). assert.h is included in php.h if it is available. 
+    Not only good assertion catch bugs, but also it makes easier to read code.
+
 Naming Conventions
 ------------------
 

configure.in

@@ -363,6 +363,7 @@ ApplicationServices/ApplicationServices.h \
 alloca.h \
 arpa/inet.h \
 arpa/nameser.h \
+assert.h \
 crypt.h \
 fcntl.h \
 grp.h \

main/php.h

@@ -63,7 +63,16 @@
 
 #include "php_regex.h"
 
-
+#if HAVE_ASSERT_H
+#if PHP_DEBUG
+#undef NDEBUG
+#else
+#define NDEBUG
+#endif
+#include <assert.h>
+#else /* HAVE_ASSERT_H */
+#define assert(expr) ((void) (0))
+#endif /* HAVE_ASSERT_H */
 
 #define APACHE 0