sizeof(needle) includes the \0 terminator, so the first letter of the
target triplet was being skipped too. This caused the architecture to
be mis-detected and (for us on MSYS2) the 32bit GDB to be selected in
64bit Kits.

Change-Id: Id54bc320baf6cc604f2d41fa7ff05aca0756a296
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Ray Donnelly <mingw.android@gmail.com>