Support specifying a dtk binary

[ribbanya]

From doldecomp/melee#1335.

[encounter]

For consistency with the other arguments, let's rename this to just --dtk

[ribbanya]

I think I'm done committing for real now.

❯ ./configure.py --help             
usage: configure.py [-h] [--version {GAMEID}] [--build-dir DIR] [--binutils BINARY] [--compilers DIR] [--map]
                    [--debug] [--wrapper BINARY] [--dtk BINARY | DIR] [--sjiswrap EXE] [--verbose]
                    [{configure,progress}]

positional arguments:
  {configure,progress}  script mode (default: configure)

options:
  -h, --help            show this help message and exit
  --version {GAMEID}    version to build
  --build-dir DIR       base build directory (default: build)
  --binutils BINARY     path to binutils (optional)
  --compilers DIR       path to compilers (optional)
  --map                 generate map file(s)
  --debug               build with debug info (non-matching)
  --wrapper BINARY      path to wibo or wine (optional)
  --dtk BINARY | DIR    path to decomp-toolkit binary or source (optional)
  --sjiswrap EXE        path to sjiswrap.exe (optional)
  --verbose             print verbose output

[encounter]

Looks great! I just caused you another merge conflict, sorry 🙃

[ribbanya]

Resolved.