The design of the build enablement flags is for PlatformEnable.h to contain the default state of flags, and for individual ports to have specific files that control the state on those platforms (assuming they do not want the default behavior). In general, features should start of enabled in some ports and not others, then be enabled on all ports, then eventually the compile option is removed and all ports just build it all the time. We have dedicated files for Playstation, Cocoa, and Windows, but the GTK/WPE port flags live inside the main PlatformEnable header, leading to confusion and encouraging developers to add more conditional flags in that "default" file. This patch adds a new PlatformEnableGTKWPE.h file that moves the relevant flags, and tidies up the primary file.