prototype for gnu strcasestr (currently a stub)

include/string.h

@@ -68,6 +68,7 @@ size_t strlcpy (char *, const char *, size_t);
 int strcasecmp (const char *, const char *);
 int strncasecmp (const char *, const char *, size_t);
 char *strchrnul(const char *, int);
+char *strcasestr(const char *, const char *);
 #endif
 
 #ifdef __cplusplus