this makes it consistent with the determination of the default
include/library paths. this makes sense, as it's possible to switch the
sdk/toolchain after building qt (within reason).
a side effect of this change is that for compilers which emulate other
compilers, both the real and the emulated version are now made
available.
Change-Id: Icfcc672c0d2e3d1b5e622993c366063d70ad327c
Started-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
