NaCl: Update revision in DEPS, r12773 -> r12779

This pulls in the following Native Client changes:

r12776: (noelallen) Replace x86 with arm toolchain in bionic tarball.
r12777: (dschuff) pnacl-translate: Don't do module splitting when using QEMU
r12778: (jvoung) Make save-temps work with pnacl-translate's split modules
r12779: (mseaborn) Provide an API for constructing an IRT, for embedders of NaCl to use

BUG=none
TEST=browser_tests and nacl_integration
TBR=jvoung@chromium.org

Review URL: https://codereview.chromium.org/170783008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@251967 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -28,7 +28,7 @@ vars = {
   "chromiumos_git": "https://chromium.googlesource.com/chromiumos",
   "skia_git": "https://skia.googlesource.com",
   "swig_revision": "230490",
-  "nacl_revision": "12773",
+  "nacl_revision": "12779",
   # After changing nacl_revision, run 'glient sync' and check native_client/DEPS
   # to update other nacl_*_revision's.
   "nacl_tools_revision": "12760",  # native_client/DEPS: tools_rev