**/Makefile.kmk: Cosmetic changes.
Installer/linux: more build_in_tmp simplificaion.
NOINST -> INSTTYPE=none; adding DEBUG_INSTTYPE=both if the NOINST was because of code signing. This will make the .PDBs be installed into stage/debug/ for signed drivers (i.e. with .INF files).
HostDrivers/VBoxPci: make it compilable without VBOX_WITH_VBOXDRV
kBuild,HostDrivers: Consolidate install targets using EXEC_SOURCES. Some cleanup, esp VBoxPci ofc.
*.kmk: Installation/staging adjustments (kBuild 0.2.0 preps).
PCI: Linux driver