ANDROID: GKI: Enable DEBUG_INFO_DWARF4

This is useful for debuggers, and is already the default for clang
(incidentally). Make sure it is on for all users/compilers.

Bug: 160841764
Change-Id: Ibb9a0c6900728d4cce3eccb57fb4c38268a89f24
Signed-off-by: Alistair Delva <adelva@google.com>