Switch default toolchain to 4.4.0 in master.
diff --git a/core/combo/linux-arm.mk b/core/combo/linux-arm.mk
index 670c4b4..ec786c0 100644
--- a/core/combo/linux-arm.mk
+++ b/core/combo/linux-arm.mk
@@ -38,7 +38,7 @@
 # You can set TARGET_TOOLS_PREFIX to get gcc from somewhere else
 ifeq ($(strip $($(combo_target)TOOLS_PREFIX)),)
 $(combo_target)TOOLS_PREFIX := \
-	prebuilt/$(HOST_PREBUILT_TAG)/toolchain/arm-eabi-4.2.1/bin/arm-eabi-
+	prebuilt/$(HOST_PREBUILT_TAG)/toolchain/arm-eabi-4.4.0/bin/arm-eabi-
 endif
 
 $(combo_target)CC := $($(combo_target)TOOLS_PREFIX)gcc$(HOST_EXECUTABLE_SUFFIX)