Deleted PC/DevSMC.cpp, removed the associated define.

SMC reimplementation (disabled). Works but needs save state, more keys and more testing.

iPXE: save a tiny bit more ROM space by ripping out the embedded image support, use it as the compiled in PXE ROM, but stick to Etherboot for OSE to avoid breakage until iPXE is included in the tree

introduced VBOX_WITH_PXE_ROM

Move the misc files the in src/VBox/Devices/ directory into a build/ subdirectory, changing their names to match the target module.