lib/libffi: Add libffi as a submodule.

pfalcon · pfalcon · commit c13be69a8e5c · 2015-10-17T15:52:35.000+03:00
This allows to build libffi from source together with micropython, and is
useful for cross-compilation. Support for this was already merged
previously, to use:

make libffi
make MICROPY_STANDALONE=1

(To both commands appropriate cross-compilition flags can be added).
diff --git a/.gitmodules b/.gitmodules
@@ -2,3 +2,6 @@
 	path = lib/axtls
 	url = https://github.com/pfalcon/axtls
 	branch = micropython
+[submodule "lib/libffi"]
+	path = lib/libffi
+	url = https://github.com/atgreen/libffi
diff --git a/lib/libffi b/lib/libffi
@@ -0,0 +1 @@
+Subproject commit e9de7e35f2339598b16cbb375f9992643ed81209
