package/gdb: bump to version 8.2.1

package/gdb: bump to version 8.2.1

GDB 8.2.1 brings the following fixes and enhancements over GDB 8.2:

 * PR build/23516 (gdb build error under msys+mingw: strip can't handle gdb-add-index.exe)
 * PR build/23623 (install-strip fails)
 * PR rust/23626 (gdb crashes in upstream rust nil-enum test)
 * PR rust/23650 (rust field name access error mentions "foo")
 * PR gdb/23663 (gdb 8.1.1: undefined rpl_stat function with musl toolchains)
 * PR python/23669 (gdb.execute("show commands") doesn't work)
 * PR python/23714 (Command repetition stops working after gdb.execute)
 * PR gdb/23838 (8.2 regression for invalid -data-directory)
 * PR gdb/23974 ("info os" crash when specifying invalid object)
 * PR gdb/23999 (SYMBOL_LANGUAGE assertion failure on AIX)
 * PR gdb/24003 (Error when binary searching CUs for a specific DIE when using DWZ)

Remove upstream patch:

0006-Move-is_regular_file-from-common-utils.c-to-filestuf.patch
https://github.com/bminor/binutils-gdb/commit/5de69bdbd0bbd7941b4cd93d4571f5e22cdb28be

See:
https://sourceware.org/ml/gdb-announce/2018/msg00004.html

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>