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/demos/perl/Makefile.PL b/third_party/gmp/demos/perl/Makefile.PL
new file mode 100644
index 0000000..a676710
--- /dev/null
+++ b/third_party/gmp/demos/perl/Makefile.PL
@@ -0,0 +1,82 @@
+# Makefile for GMP perl module.
+
+# Copyright 2001, 2003, 2004 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/.
+
+
+# Bugs:
+#
+# When the generated Makefile re-runs "perl Makefile.PL" the GMP_BUILDDIR
+# parameter is lost.
+
+
+use ExtUtils::MakeMaker;
+
+
+# Find and remove our parameters
+@ARGV = map {
+  if (/^GMP_BUILDDIR=(.*)/) {
+    $GMP_BUILDDIR=$1; ();
+  } else {
+    $_;
+  }
+} (@ARGV);
+
+$INC = "";
+$LIBS = "-lgmp";
+$OBJECT = "GMP.o";
+
+if (defined $GMP_BUILDDIR) {
+  if (! -f "$GMP_BUILDDIR/libgmp.la") {
+    die "$GMP_BUILDDIR doesn't contain libgmp.la\n" .
+	"if it's really a gmp build directory then go there and run \"make libgmp.la\"\n";
+  }
+  $INC = "-I$GMP_BUILDDIR $INC";
+  $LIBS = "-L$GMP_BUILDDIR/.libs $LIBS";
+}
+
+WriteMakefile(
+	      NAME         => 'GMP',
+	      VERSION      => '2.00',
+	      LIBS         => [$LIBS],
+	      OBJECT       => $OBJECT,
+	      INC          => $INC,
+	      clean        => { FILES => 'test.tmp' },
+	      PM => {
+		'GMP.pm'      => '$(INST_LIBDIR)/GMP.pm',
+		'GMP/Mpz.pm'  => '$(INST_LIBDIR)/GMP/Mpz.pm',
+		'GMP/Mpq.pm'  => '$(INST_LIBDIR)/GMP/Mpq.pm',
+		'GMP/Mpf.pm'  => '$(INST_LIBDIR)/GMP/Mpf.pm',
+		'GMP/Rand.pm' => '$(INST_LIBDIR)/GMP/Rand.pm',
+	      }
+	      );
+
+
+# Local variables:
+# perl-indent-level: 2
+# End: