ruby: Fix x86-64 build

packages/ruby/src-signal.c.patch

@@ -0,0 +1,14 @@
+REG_RSP is an enum value in the NDK so cannot be ifdef checked.
+
+diff -u -r ../ruby-2.3.1/signal.c ./signal.c
+--- ../ruby-2.3.1/signal.c	2015-11-23 19:17:11.000000000 -0500
++++ ./signal.c	2016-06-17 17:15:18.947494468 -0400
+@@ -771,7 +771,7 @@
+ {
+     const DEFINE_MCONTEXT_PTR(mctx, ctx);
+ # if defined __linux__
+-#   if defined REG_RSP
++#   if defined __x86_64__
+     const greg_t sp = mctx->gregs[REG_RSP];
+ #   else
+     const greg_t sp = mctx->gregs[REG_ESP];