AndroidBoot.mk: build host tools with clang

The old gcc 4.8 continues to degrade with newer host utilies, so switch
to clang instead.

Issue: FP2A10-200
Test: m out/target/product/FP2/emmc_appsboot.mbn
Change-Id: I4b7a87e174172c73f8be993fb2af141360fc7183
2 files changed