Revert temporary commits to be able to use the bootstrap compiler which is compiled without optimized instance calls
Optimized instance calls are now enabled by default in the compiler (clean-compiler-and-rts/compiler@bfbbd3f2), but combining old ABC code (without optimized instance calls) and new ABC code (with optimized instance calls) will lead to segmentation faults. This happened in the second pass of building the Clean system: the first pass builds the new system, but the old ABC of StdEnv remains. With this commit a new StdEnv is built before doing the second pass, to avoid segmentation faults in the newly built compiler and cpm.
Eventually these commits should be reverted (for instance, a fix could be to have a new bootstrap compiler that generates optimized instance calls).