Allow user to override the linux host toolchain.

# Previously the prebiult host toolchain is used only for the sdk build,

# that's why we have "sdk" in the path name.

ifeq ($(strip $(HOST_TOOLCHAIN_PREFIX)),)

HOST_TOOLCHAIN_PREFIX := prebuilts/tools/gcc-sdk

endif

# Don't do anything if the toolchain is not there

ifneq (,$(strip $(wildcard $(HOST_TOOLCHAIN_PREFIX)/gcc)))

HOST_CC  := $(HOST_TOOLCHAIN_PREFIX)/gcc