netperfmeter fails to cross build from source, because it uses
CHECK_C_SOURCE_RUNS twice. While the first invocation really benefits
from running code, the second invocation merely validates a few compile
time constants. The test does not degrade by using
CHECK_C_SOURCE_COMPILES instead. The latter macro is compatible with
cross compilation though. I'm attaching a patch for it.

This does not make netperfmeter cross buildable out of the box, but it
reduces the configuration a builder has to supply to
USES_IEEEFP_FP_EXITCODE, so please close the bug once improving this
aspect.

Helmut