On Windows, typeids are different between DLLs and EXEs, so comparing
type_info* will work for typeids from the same compiled file but fail
for typeids from a DLL and an executable. Among other things, exceptions
are not caught by handlers since can_catch() returns false.

Defining _LIBCXX_DYNAMIC_FALLBACK does not help since can_catch() calls
is_equal() with use_strcmp=false so the string names are not compared.

This patch compares typeids first (cheap) and only they are different
calls strcmp.