Replace external/srec path to new repository android_external_srec

Change-Id: I8c56c0f91374b4f2bf37524573e3c7cd487aea28
Replace external/llvm path to new repository android_external_llvm

Change-Id: Ib3ab5846aa2c7dcfe2e0bfdba8d0cb171e1a2261
Merge changes Ib3ab5846,I8c56c0f9 into android-4.3

* changes:
  Replace external/llvm path to new repository android_external_llvm
  Replace external/srec path to new repository android_external_srec