JBigI: GMP 6.1.2 for linux 64 bit (ticket #1869)

Adds Broadwell and Skylake binaries
Updates all other linux 64 bit binaries
32 bit libraries will not be updated
Other OS 64 bit binaries may or may not follow at a later date

LICENSE.txt

@@ -184,7 +184,7 @@ Jbigi Libraries (jbigi.jar):
    GMP 4.3.2 / 5.0.2:
    Copyright 1991, 1996, 1999, 2000, 2007 Free Software Foundation, Inc.
    See licenses/LICENSE-LGPLv3.txt
-   GMP 6.0.0:
+   GMP 6.0.0 / 6.1.2:
    See licenses/LICENSE-GPLv2.txt