K 10 svn:author V 3 imp K 8 svn:date V 27 2014-03-30T22:24:45.659779Z K 7 svn:log V 390 Allow the build system to safely set MK_FOO to avoid the ambiguity when both WITH_FOO and WITHOUT_FOO are set. Use this where possible. Only disallow setting of MK_FOO on the command line. This was preferable to inventing a new mechanism or fixing the undef bug (bin/183762) which precludes users from turning off anything we turn off for parts of the build with WITHOUT_FOO prior to this. END