Backed out changeset a25bfa87418d (using std::type_info::name())

The changeset above touched every consumer of the two LLRegistrySingletons
originally defined with std::type_info* as keys. Those two
LLRegistrySingletons were changed to use const char* as keys, then all
consumers were changed to pass std::type_info::name() instead of the plain
std::type_info* pointer -- to deal with the observed fact that on Linux, a
given type might produce different std::type_info* pointers in different load
modules. Since then, Richard turned up the fascinating fact that at least some
implementations of gcc's std::type_info::before() method already accommodate
this peculiarity. It seems worth backing out the (dismayingly pervasive)
change to see if properly using std::type_info::before() as the map comparator
will work just as well, with conceptually simpler source code.
This backout is transitional: we don't expect things to build/run properly
until we've cherry-picked certain other pertinent changes.