J2SE_MKTG_VERSION is defined in make/common/shared/Defs.gmk to have the value
$(JDK_MINOR_VERSION).$(JDK_MICRO_VERSION). As of Mustang it should really be
just $(JDK_MINOR_VERSION) since we've dropped the ".0".

I considered fixing this as part of 6332764 but I was reluctant to do so since
J2SE_MKTG_VERSION, and variables derived from it, are used in makefiles across
the various workspaces and I don't have the resources to do all of the required
test builds.