Add support for gdb 8.1

Hello,

Here is finally a respin of the gdb 8.1 support.

Changes since v2:

- Rework "package/gdb: rework dependency for C++11" to fix issues pointed out during the review. The BR2_PACKAGE_GDB_NEEDS_CXX11 blind option is moved to package/gdb/Config.in.host, and calculated differently. A comment is added on top of it to explain the logic behind it.

- Fix build of gdb 8.1 with uclibc/musl caused by gnulib not detecting the availability of strerror().

- Re-add patches from gdb 8.0.1 that are still valid, i.e all patches, except one that has been merged upstream.

Arnout suggested that we should probably remove the version selection for gdb. For now, I've kept it as it is, I believe it's a separate discussion. gdb 8.1 has been released in January 2018, i.e 6 months ago, it's time to merge support for it.

Thanks,

Thomas

Romain Naour (4):
package/gdb: bump to version 8.1 package/gdb: switch to 8.0 as the default version package/gdb: remove 7.10
package/gdb: remove 7.11

Thomas Petazzoni (1):
package/gdb: rework dependency for C++11

 Config.in.legacy                                   | 14 +++++
 ...Define-pt_regs-uapi_pt_regs-on-GLIBC-syst.patch | 55 +++++++++++++++++++
 ...efine-pt_-dsp-regs-uapi_pt_-dsp-regs-on-G.patch | 43 +++++++++++++++
 package/gdb/8.1/0003-use-asm-sgidefs.h.patch       | 40 ++++++++++++++
 .../8.1/0004-gdbserver-fix-build-for-m68k.patch    | 62 ++++++++++++++++++++++
 package/gdb/Config.in                              |  8 +++
 package/gdb/Config.in.host                         | 37 ++++++++-----
 package/gdb/gdb.hash                               |  3 +-
 package/gdb/gdb.mk                                 | 14 ++++-
 9 files changed, 260 insertions(+), 16 deletions(-)
 create mode 100644 package/gdb/8.1/0001-ppc-ptrace-Define-pt_regs-uapi_pt_regs-on-GLIBC-syst.patch
 create mode 100644 package/gdb/8.1/0002-sh-ptrace-Define-pt_-dsp-regs-uapi_pt_-dsp-regs-on-G.patch
 create mode 100644 package/gdb/8.1/0003-use-asm-sgidefs.h.patch
 create mode 100644 package/gdb/8.1/0004-gdbserver-fix-build-for-m68k.patch

2.14.4