adbd: remove static dependency on libcutils.

We were previously statically linking libcutils into adbd for several
different reasons, which were addressed as follows:

  socket functions: extracted to a statically linked libcutils_network
  fs_config: wrapped with a shared library on /system
  ATRACE: deleted the single use in adbd

Test: treehugger
Change-Id: I821fa174cfcbfa8e29a4be10de4016b817adbaf8