avoid conflict with string.h

--- perdition/str.h.orig	Sat Nov 13 10:42:15 2010
+++ perdition/str.h	Sat Nov 13 10:42:24 2010
@@ -351,7 +351,7 @@ char *str_replace(char *str, size_t n, ...);
  *       the time.
  **********************************************************************/
 
-const char *strcasestr(const char *haystack, const char *needle);
+const char *perdition_strcasestr(const char *haystack, const char *needle);
 
 /**********************************************************************
  * strcasedelimword