Revert "Enable LTO in cargo2android.py."

This reverts commit 4f4ac2f8f309db10c7ccc4c8e4e8979fc803b249.

This did not work for all crates (specifically, those with build.rs,
as they don't get passed RUSTFLAGS, as well as proc-macros, since they
get the flag but can't use LTO), so we're using a different approach
where this is not desired.

Test: Run script
Change-Id: Ib1a86d4822f51978cd8ec15ad657eb25c84e01a4
1 file changed