Revert "Remove gmp from AOS"

This reverts commit f37c97684f0910a3f241394549392f00145ab0f7.

We need gmp for SymEngine for symbolicmanipultion in C++

Change-Id: Ia13216d1715cf96944f7b4f422b7a799f921d4a4
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
diff --git a/third_party/gmp/mpz/cmp.c b/third_party/gmp/mpz/cmp.c
new file mode 100644
index 0000000..a97b004
--- /dev/null
+++ b/third_party/gmp/mpz/cmp.c
@@ -0,0 +1,53 @@
+/* mpz_cmp(u,v) -- Compare U, V.  Return positive, zero, or negative
+   based on if U > V, U == V, or U < V.
+
+Copyright 1991, 1993, 1994, 1996, 2001, 2002, 2011 Free Software Foundation,
+Inc.
+
+This file is part of the GNU MP Library.
+
+The GNU MP Library is free software; you can redistribute it and/or modify
+it under the terms of either:
+
+  * the GNU Lesser General Public License as published by the Free
+    Software Foundation; either version 3 of the License, or (at your
+    option) any later version.
+
+or
+
+  * the GNU General Public License as published by the Free Software
+    Foundation; either version 2 of the License, or (at your option) any
+    later version.
+
+or both in parallel, as here.
+
+The GNU MP Library is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received copies of the GNU General Public License and the
+GNU Lesser General Public License along with the GNU MP Library.  If not,
+see https://www.gnu.org/licenses/.  */
+
+#include "gmp-impl.h"
+
+int
+mpz_cmp (mpz_srcptr u, mpz_srcptr v) __GMP_NOTHROW
+{
+  mp_size_t  usize, vsize, dsize, asize;
+  mp_srcptr  up, vp;
+  int        cmp;
+
+  usize = SIZ(u);
+  vsize = SIZ(v);
+  dsize = usize - vsize;
+  if (dsize != 0)
+    return dsize;
+
+  asize = ABS (usize);
+  up = PTR(u);
+  vp = PTR(v);
+  MPN_CMP (cmp, up, vp, asize);
+  return (usize >= 0 ? cmp : -cmp);
+}