pymake: don't abort() on exception in job worker

abort() is a bit too strong, instead just call _exit()
with a failure exit code.
pymake: add ObjectArchiver() recipe
pymake: record compiler command used in CPPIncludes() cache

Since CPPIncludes() can be generated using differen C(XX)FLAGS
we should record which compiler command we used to know when
to invalidate the cached file.