mkfontscale requires x11-misc/util-macros otherwise, a make error will occur when config fails to find xorg-macros within the pkg-config search path. This error occurred on the initial build, while installing cups, and will generally be masked if mkfontscale is being installed after xorg has been explicitly installed, but arises when emerging a dependent package (such as CUPS) during an initial build, before all of xorg is installed.
Fixed in mkfontscale-1.1.2.