Updated CMakeLists.txt to use the new FlatBuffers build rules.
Updated CMakeLists.txt to use the new FlatBuffers build rules.

This library no longer needs to copy any schema files, as the new
build rules handle this where required.

Change-Id: I78413c7222f4a0b7f827058bbc6a59d607740764
Tested: Linux desktop build completed.

google/corgi,google/corgi