git-gui on Windows uses auto_execok to locate git-gui.exe,
which performs the same flawed search as does the builtin exec.
Use _which instead, performing a safe PATH lookup.
Signed-off-by: Mark Levedahl <mlevedahl@gmail.com>
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Taylor Blau <me@ttaylorr.com>