Fix a warning for 'ffs' function on AIX7.

The warning was:
./optimize.c: In function 'opt_j':
./optimize.c:1359:4: warning: implicit declaration of function 'ffs' [-Wimplicit
-function-declaration]
    k = ffs(x) - 1;
    ^

1 files changed, 23 insertions, 0 deletions

diff --git a/lbl/os-aix7.h b/lbl/os-aix7.h
new file mode 100644
index 00000000..93b12f2d
--- /dev/null
+++ b/lbl/os-aix7.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 1993, 1994, 1995, 1996, 1997
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code distributions
+ * retain the above copyright notice and this paragraph in its entirety, (2)
+ * distributions including binary code include the above copyright notice and
+ * this paragraph in its entirety in the documentation or other materials
+ * provided with the distribution, and (3) all advertising materials mentioning
+ * features or use of this software display the following acknowledgement:
+ * ``This product includes software developed by the University of California,
+ * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+ * the University nor the names of its contributors may be used to endorse
+ * or promote products derived from this software without specific prior
+ * written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+/* Prototypes missing in AIX 7.x */
+int	ffs(int i);