5798 fexecve() needed per POSIX 2008

@@ -421,10 +421,13 @@
 int fattach(int fildes, const char *path);
 
 /* fdetach.c */
 int fdetach(const char *path);
 
+/* fexecve.c */
+int fexecve(int, char *const argv[], char *const envp[]);
+
 /* ffs.c */
 int ffs(int field);
 
 /* fmtmsg.c */
 int addseverity(int value, const char *string);