Revert "Build and execute cpp-define-generate before build aosp"

Bug: http://b/62869798

This reverts commit a440a26c.  The
checked-in ART header was updated as part of the toolchain update.

Test: toolchain/llvm/android/test_compiler.py --build-only \
          --target aosp_marlin-eng --no-clean-built-target ./

Change-Id: I65091608970d65413f76337ac1724d267b24b15c