There is a "version suffix" that defaults to "-dev". A maintainer could
change the suffix (or remove it) by invoking make:
make BUILD_SUFFIX=-foo
make BUILD_SUFFIX=
It can also be changed in gyp builds:
gyp winpty.gyp --depth=1 -D BUILD_SUFFIX=-foo
gyp winpty.gyp --depth=1 -D BUILD_SUFFIX=
If git cannot be executed, the string "none" is used for the commit hash.
