Export TARGET_GCC_VERSION as an env variable.

Have it referenced by the adbs tool to pick the specified toolchain.

Change-Id: I23df88946254a55d0749d6753e54559faf33e121
diff --git a/envsetup.sh b/envsetup.sh
index 1b70d10..a88d8ce 100644
--- a/envsetup.sh
+++ b/envsetup.sh
@@ -118,6 +118,7 @@
 
     # defined in core/config.mk
     targetgccversion=$(get_build_var TARGET_GCC_VERSION)
+    export TARGET_GCC_VERSION=$targetgccversion
 
     # The gcc toolchain does not exists for windows/cygwin. In this case, do not reference it.
     export ANDROID_EABI_TOOLCHAIN=