edk2: Fix compilation errors on latest Android

1) Update HOST tools with CLANG, since gcc is no longer supported.
2) Suppress the warnings of shift negative values.
3) Use Python & LD from prebuilds.
4) Backward compatible with existing baselines.

Change-Id: I9fdeaec7d4cdc95997f07fd05a47c67c1177cb2d
6 files changed