Add libgmp 6.2.0 to third_party

Don't build it yet.  That will come in the next review.

Change-Id: Idf3266558165e5ab45f4a41c98cc8c838c8244d5
diff --git a/third_party/gmp/mini-gmp/tests/hex-random.h b/third_party/gmp/mini-gmp/tests/hex-random.h
new file mode 100644
index 0000000..da44347
--- /dev/null
+++ b/third_party/gmp/mini-gmp/tests/hex-random.h
@@ -0,0 +1,55 @@
+/*
+
+Copyright 2011, 2018 Free Software Foundation, Inc.
+
+This file is part of the GNU MP Library test suite.
+
+The GNU MP Library test suite is free software; you can redistribute it
+and/or modify it under the terms of the GNU General Public License as
+published by the Free Software Foundation; either version 3 of the License,
+or (at your option) any later version.
+
+The GNU MP Library test suite 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 a copy of the GNU General Public License along with
+the GNU MP Library test suite.  If not, see https://www.gnu.org/licenses/.  */
+
+enum hex_random_op
+  {
+    OP_ADD, OP_SUB, OP_MUL, OP_SQR,
+    OP_CDIV, OP_FDIV, OP_TDIV,
+    OP_CDIV_Q_2, OP_CDIV_R_2,
+    OP_FDIV_Q_2, OP_FDIV_R_2,
+    OP_TDIV_Q_2,  OP_TDIV_R_2,
+    OP_GCD, OP_LCM, OP_POWM, OP_AND, OP_IOR, OP_XOR,
+    OP_SETBIT, OP_CLRBIT, OP_COMBIT,
+    OP_SCAN0, OP_SCAN1,
+  };
+
+void hex_random_init (void);
+char *hex_urandomb (unsigned long bits);
+char *hex_rrandomb (unsigned long bits);
+char *hex_rrandomb_export (void *dst, size_t *countp,
+			   int order, size_t size, int endian,
+			   unsigned long bits);
+
+void hex_random_op2 (enum hex_random_op op,  unsigned long maxbits,
+		     char **ap, char **rp);
+void hex_random_op3 (enum hex_random_op op,  unsigned long maxbits,
+		     char **ap, char **bp, char **rp);
+void hex_random_op4 (enum hex_random_op op,  unsigned long maxbits,
+		     char **ap, char **bp, char **rp, char **qp);
+void hex_random_bit_op (enum hex_random_op op, unsigned long maxbits,
+			char **ap, unsigned long *b, char **rp);
+void hex_random_scan_op (enum hex_random_op op, unsigned long maxbits,
+			char **ap, unsigned long *b, unsigned long *r);
+void hex_random_str_op (unsigned long maxbits,
+			int base, char **ap, char **rp);
+void hex_random_lucm_op (unsigned long maxbits,
+			 char **vp, char **qp, char **mp,
+			 long *Q, unsigned long *b0, int *res);
+void hex_mpq_random_str_op (unsigned long maxbits,
+			    int base, char **ap, char **rp);