Can LAL_SYSTEM_INCLUDES be removed?

The build infrastructure is configured to create a variable LAL_SYSTEM_INCLUDES that is then appended to CPPFLAGS to help the SWIG builds.

In my experience all this does is add -I/usr/include to CPPFLAGS which seems like a really bad idea in general; if that directory is required, it should be picked up by pkg-config. It definitely breaks conda-based top-level builds on my Debian-based system.

So, since this is only used by SWIG, can this be removed?