Move xgetpwuid() and xgetgrgid() into xwrap.c
diff --git a/lib/lib.h b/lib/lib.h
index a0a1c31..e5d4a1d 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -111,6 +111,8 @@
 void xchdir(char *path);
 void xmkpath(char *path, int mode);
 void xsetuid(uid_t uid);
+struct passwd *xgetpwuid(uid_t uid);
+struct group *xgetgrgid(gid_t gid);
 char *xreadlink(char *name);
 long xparsetime(char *arg, long units, long *fraction);
 void xpidfile(char *name);