By running the grep command `git grep -nr 'define \(fpscr\|msr\)_[a-z0-9]\+\>'`
we can find multiple macros that use `env->fpscr` and `env->msr` but doesn't
take *env as a parameter.
Richard Henderson said [1] that these macros hiding the usage of *env "are
evil".
This patch series remove them and substitute with an explicit usage of *env by
adding macros in the same style of FP_* ones (e.g. FP_FI defined in cpu.h).
Patch 20 (target/ppc: Add unused M_MSR_* macros) implements unused macros, the
same that were removed in patch 02 (target/ppc: Remove unused msr_* macros). I
did that to keep the changes consistent with what was already present before.