removed outdated IsDebuggerPresent declaration

This piece of code seems to retain compatibility with some windows
versions before 2000. Today it's not relevant anymore and only
produces a warning C4273 because of the conflicting prototype. In
VC9 the declaration is present in winbase.h:4142, but available
is it already in winxp. Here's the doc link
http://msdn.microsoft.com/en-us/library/windows/desktop/ms680345(v=vs.85).aspx

Author: weltling

Zend/zend.c

@@ -43,10 +43,6 @@
 # define GLOBAL_CONSTANTS_TABLE		EG(zend_constants)
 #endif
 
-#if defined(ZEND_WIN32) && ZEND_DEBUG
-BOOL WINAPI IsDebuggerPresent(VOID);
-#endif
-
 /* true multithread-shared globals */
 ZEND_API zend_class_entry *zend_standard_class_def = NULL;
 ZEND_API int (*zend_printf)(const char *format, ...);