Remove regeneration of ABC code of system modules
After clean-compiler-and-rts/stdenv@dfe469d7, StdEnv system modules contained syntax that is not recognized by the bootstrap compiler. This caused the build to fail when regenerating the ABC code for StdEnv during the first pass. I added 4d0d4dea which makes sure that this ABC is only regenerated in the second pass, when the new compiler is used.
Ultimately all this code should be removed when precompilation of this modules is not needed any more. It is used for inlining, but now that the ABC code is present in the definition module I believe inlining can be done without precompilation.