Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Support restrict qualifier in dwarf debug info

Newer clang/llvm emit DW_TAG_restrict_type, which wasn't handled by gdb.
Import support from Apple's gdb-1822:

| 2009-03-24 Jason Molenda (jmolenda@apple.com)
|
| * gdbtypes.c (make_cv_type): Rename this function to make_cvr_type to
| also handle restrict qualifiers.
| (check_typedef): Handle TYPE_RESTRICT.
| * gdbtypes.h (TYPE_FLAG_RESTRICT, TYPE_RESTRICT): New.
| * hpread.c (hpread_type_lookup): Update to use make_cvr_type.
| * stabsread.c (read_type): Pass the restrict qualifiers along.
| * parse.c (follow_types): Pass the restrict qualifiers along.
| * dwarf2read.c (read_tag_const_type): Call make_cvr_type.
| (read_tag_volatile_type): Same.
| (read_tag_restrict_type): New function.
| (read_type_die): Handle DW_TAG_restrict_type.

Obtained from: Apple
Sponsored by: ADARA Networks

This commit was generated by cvs2svn to compensate for changes in r130803,
which included commits to RCS files with non-trunk default branches.

Import of GDB version 6.1.1 (stripped; see FREEBSD-Xlist rev. 1.6).