Add crosstool-NG submodule.

From https://github.com/jcmvbkbc/crosstool-NGcrosstool-NG , branch lx106-g++

.gitmodules

@@ -0,0 +1,4 @@
+[submodule "crosstool-NG"]
+	path = crosstool-NG
+	url = https://github.com/jcmvbkbc/crosstool-NG
+	branch = lx106-g++

crosstool-NG

@@ -0,0 +1 @@
+Subproject commit d30ecd31fba25ccf768a0c1c4d52a16d8680bc82