remove support for *.mc files

We've also removed the last consumer of .mc files in aosp/1867048
(external/mdnsresponder/).

Bug: 203794880
Test: lunch aosp_cf_x86_64_phone-userdebug && m
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Change-Id: I2883a04d04b099273261d76319261d0857aa0300