We have a rather odd precompiled logic. If PCH is enabled, we include additional headers in the PCH. If not, we don't. This is why we get
header incompatibilities between PCH/noPCH builds (since all our .cpp files include the precompiled header).
By removing this, we remove these issues.
Further, the MINIMAL_PCH logic is weird. I rename it to PCH_LEVEL and make it more understandable.