rt-tests v1.9 fails to compile on architectures that aren't x86_64, i386 or PPC64

[Randy Witt <randy.e.witt@xxxxxxxxxxxxxxx>]

With the addition of the oslat test in v1.9, "make" with no arguments will fail 
on any architecture that isn't x86_64, i386 or PPC64. This is due to the #error 
added here 
https://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git/tree/src/oslat/oslat.c?h=v1.9#n72.

Since there is no build time configuration to turn off particular tests, is the 
expected workflow to specify the set of desired tests as make arguments?

In the absence of some sort of configure script, should there be a variable that 
allows for tests to be removed from the set of TARGETS?