Continue using the real make if -C is used

To allow building other make-based systems from the top of the android
tree.

Bug: 64145979
Test: get_make_command
Test: get_make_command -C
Test: get_make_command -C.
Test: get_make_command -C .
Test: get_make_command -j test
Test: get_make_command test-C
Test: get_make_command " -C"
Test: make
Test: make -C.
Change-Id: I406dd2706f19e5d2a6afdff441335f4e01ba6d12