Some users would like to use the empty font manager, but the directory
gont manager brings in extra dependencies to work which would otherwise
be unneeded. Allow these users to build just the bits of code they
actually need.
Change-Id: Ib029ef2682883509bad5a2aa39f1ef55631f4d8a
Reviewed-on: https://skia-review.googlesource.com/8200
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
