Now that the build is non-recursive, adding to AM_CPPFLAGS means adding to
_all_ cppflags.
Logical groups of includes have been added instead, and are used individually
by various targets.
- Some file generation was still noisy, silence it.
- AM_V_GEN is used rather than @ so that 'make V=1' works as intended
- Cut down on file copies and moves when using sed, use pipes instead
- Avoid the use of top_ and abs_ dirs where possible
Build logic moves from individual Makefile.am's to include files, which
the main src/Makefile.am includes. This avoids having to manage a gigantic
single Makefile.
TODO: Move the rules from the old Makefile.include to where they actually
belong and nuke the old file.
