Since the type whose name is being set is now being allocated on the
gdbarch obstack, we should allocate its TYPE_NAME on the obstack too.
This reduces the number of individual valgrind warnings for the command
"gdb gdb" from ~300 to ~150.
Tested on x86_64-unknown-linux-gnu.
gdb/ChangeLog:
* gdb_obstack.h (obstack_strdup): Declare.
* gdb_obstack.c (obstack_strdup): Define.
* gdbarch.sh (gdbarch_obstack_strdup): Declare and define.
* gdbarch.c: Regenerate.
* gdbarch.h: Regenerate.
* gdbtypes.c (arch_type): Use gdbarch_obstack_strdup.