gdb: bump to 8.3.1

gdb: bump to 8.3.1

GDB 8.3.1 brings the following fixes and enhancements over GDB 8.3:

PR c++/20020 (GDB segfault on printing objects)
PR gdb/24454 (nat/x86-linux-dregs.c failed assertion)
PR breakpoints/24541 (Incorrect evaluation of systemtap probes due to register being signed and probe expression assuming unsigned)
PR symtab/24545 (Symbol loading performance regression with cc1)
PR gdb/24592 (amd64->i386 linux syscall restart problem)
PR gdb/25009 (terminate called after throwing an instance of 'srchilite::ParserException')
PR gdb/25010 (Calls to error () can cause SIGTTOU to send gdb to the background)
PR breakpoints/25011 (Breakpoints on file reloads broken for PIE binaries)

This corrective release also brings the following testsuite fixes and
enhancements:

PR testsuite/25005 (gdb-caching-proc.exp takes a lot of time on skip_opencl_tests)
PR testsuite/25016 (Test-case failures for -pie)

GDB 8.3 includes the following changes and enhancements:

* Support for new native configurations (also available as a target configuration):
     - RISC-V GNU/Linux (riscv*-*-linux*)
     - RISC-V FreeBSD (riscv*-*-freebsd*)

* Support for new target configurations:
     - CSKY ELF (csky*-*-elf)
     - CSKY GNU/Linux (csky*-*-linux)
     - NXP S12Z ELF (s12z-*-elf)
     - OpenRISC GNU/Linux (or1k*-*-linux*)

* Native Windows debugging is only supported on Windows XP or later.

* The Python API in GDB now requires Python 2.6 or later.

* GDB now supports terminal styling for the CLI and TUI.
  Source highlighting is also supported by building GDB with GNU
  Highlight.

* Experimental support for compilation and injection of C++ source
  code into the inferior (requires GCC 7.1 or higher, built with
  libcp1.so).

* GDB and GDBserver now support IPv6 connections.

* Target description support on RISC-V targets.

* Various enhancements to several commands:
     - "frame", "select-frame" and "info frame" commands
     - "info functions", "info types", "info variables"
     - "info thread"
     - "info proc"
     - System call alias catchpoint support on FreeBSD
     - "target remote" support for Unix Domain sockets.

* Support for displaying all files opened by a process

* DWARF index cache: GDB can now automatically save indices of DWARF
  symbols on disk to speed up further loading of the same binaries.

* Various GDB/MI enhancements.

* GDBserver on PowerPC GNU/Linux now supports access to the PPR,
  DSCR, TAR, EBB/PMU, and HTM registers.

* Ada task switching support when debugging programs built with
  the Ravenscar profile added to aarch64-elf.

* GDB in batch mode now exits with status 1 if the last executed
  command failed.

* Support for building GDB with GCC's Undefined Behavior Sanitizer.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>