minadbd: avoid overrriding services_to_fd.

Previously, we were relying on linker ordering pulling in minadbd's
copy of services_to_fd instead of libadbd's, which breaks when we
switch to dynamically linking. Separate out libadbd's services into a
separate function that's in a file that isn't built into libadbd, so
that we can provide our own here.

Bug: http://b/111831478
Test: mma
Change-Id: I2479947b2d81db5e750020fffc2c2c770cb31a78