gdb: bump to 8.1.1

gdb: bump to 8.1.1

GDB 8.1.1 brings the following fixes and enhancements over GDB 8.1:

 * PR gdb/22824 (misleading description of new rbreak Python function in GDB 8.1 NEWS file)
 * PR gdb/22849 (ctrl-c doesn't work in extended-remote)
 * PR gdb/22907 ([Regression] gdbserver doesn't work with filename-only binaries)
 * PR gdb/23028 (inconsistent disassemble of vcvtpd2dq)
 * PR gdb/23053 (Fix -D_GLIBCXX_DEBUG gdb-add-index regression)
 * PR gdb/23127 ([AArch64] GDB cannot be used for debugging software that uses high Virtual Addresses)
 * PR server/23158 (gdbserver no longer functional on Windows)
 * PR breakpoints/23210 ([8.1/8.2 Regression] Bogus Breakpoint address adjusted from 0xf7fe7dd3 to 0xfffffffff7fe7dd3)

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