[4.5] [RFC] Move line-map.* to its own library (libloc)

[Ralf Wildenhues]

BTW, even with the desire/need to separate the code into its own
library, I completely fail to see why it needs to be in a separate
directory, with a separate configure script and separate makefile.

You don't do such things below gcc/, and they are certainly not
required from the build system.  And IIUC you are not going to use
libloc as a stand-along library (i.e., independent of GCC) anyway,
right?

Cheers,
Ralf