debug/gdb: simplify the dependency logic

Signed-off-by: Cody P Schafer <dev@codyps.com>
Message-Id: <1d9659fcf6a9c7694ad2.1399687691@localhost>
Patchwork-Id: 347583

 # windows config options

 ## depends on ARCH_x86

 ##

 ## select WINDOWS

 ##

 ## help Build a toolchain targeting systems running Windows as host