Speedup and simplify pass registration by the observation that there is

exactly one PassInfo object per RegisterPass object and that their lifetimes
are the same.  As such, there is no reason for the RegisterPass object to
dynamically allocate the PassInfo object at compiler startup time: just inline
the object by-value.  This should reduce codesize, heap size, and startup time. Yaay.

llvm-svn: 25521