Add glfw and glfw-rs to servo build.

.gitmodules

@@ -94,3 +94,9 @@
 [submodule "src/support/nss/nspr"]
 	path = src/support/nss/nspr
 	url = git://github.com/mozilla-servo/nspr.git
+[submodule "src/support/glfw/glfw"]
+	path = src/support/glfw/glfw
+	url = https://github.com/mozilla-servo/glfw.git
+[submodule "src/support/glfw/glfw-rs"]
+	path = src/support/glfw/glfw-rs
+	url = https://github.com/mozilla-servo/glfw-rs.git

configure

@@ -403,6 +403,8 @@ CFG_SUBMODULES="\
     support/css/rust-css \
     support/geom/rust-geom \
     support/glut/rust-glut \
+    support/glfw/glfw \
+    support/glfw/glfw-rs \
     support/harfbuzz/rust-harfbuzz \
     support/http-client/rust-http-client \
     support/hubbub/libhubbub \