Switch default gcc toolchain from 4.4.3 to 4.6.

Switch both arm-linux-androideabi toolchainand arm-eabi toolchain.

Change-Id: I7b2771fe684853ab37e3b5b7cfe4146f9f901e02
diff --git a/core/combo/TARGET_linux-arm.mk b/core/combo/TARGET_linux-arm.mk
index 711041d..ca12ba2 100644
--- a/core/combo/TARGET_linux-arm.mk
+++ b/core/combo/TARGET_linux-arm.mk
@@ -43,7 +43,7 @@
 
 # You can set TARGET_TOOLS_PREFIX to get gcc from somewhere else
 ifeq ($(strip $(TARGET_TOOLS_PREFIX)),)
-TARGET_TOOLCHAIN_ROOT := prebuilt/$(HOST_PREBUILT_TAG)/toolchain/arm-linux-androideabi-4.4.x
+TARGET_TOOLCHAIN_ROOT := prebuilts/gcc/$(HOST_PREBUILT_TAG)/arm/arm-linux-androideabi-4.6
 TARGET_TOOLS_PREFIX := $(TARGET_TOOLCHAIN_ROOT)/bin/arm-linux-androideabi-
 endif