* mips-tdep.c, mipsread.c, tm-mips.h: Get rid of ".gdbinfo."

* mips-tdep.c, mipsread.c, tm-mips.h:  Get rid of ".gdbinfo."
symbol.  #define MIPS_EFI_SYMBOL_NAME instead.  Use different
value so that demangler won't be invoked.  This greatly speeds up
stepping.
* mips-tdep.c (mips_pop_frame):  Rewrite handling of
linked_proc_info so that it properly deallocates the appropriate
item after it is done with it instead of before.
* Don't pass bogus frame pointer to create_new_frame().  Just
leave it as zero so that lower level code will figure out the
correct value.