Use setup makefile + make by default to build libraries
The advantages of this are (a) it's a step closer to getting -j working again (make -j works in an individual library, but not in libraries/ yet). (b) it's easier to hack on libraries: make dist/build/Foo.o (c) it's a step closer to getting HC bootstrapping again The build system creates <lib>/GNUmakefile as part of 'make boot'. This was chosen so as not to interfere with existing Makefiles, but it's a bit of a hack. (previously I used CabalMakefile, but that means adding -f CabalMakefile each time you run make, and that's a pain).