start eating include_dirs from both ends

Further restrictions on a restricting build configuration. Before, we
restricted certain paths from being included. Now, we restrict certain
paths from including.

This adds system/libfmq for now, but I'm planning to add more in the
future, as they are cleaned up.

Bug: 35624006
Test: m nothing
Change-Id: I913f190f93ab63059ee0372d342daa8f5584806b