Correct error in Makefile generation for Windows MinGW.

Remove the build_pass check that was added for vcproj
generation as it is no longer deemed necessary.

See http://trac.webkit.org/changeset/62264 and
http://trac.webkit.org/changeset/59266 for context.

Task-number: QTBUG-27413
Change-Id: Ie82032cf4b183b31c66defc2d49cc8095989ec8f
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>