This helps to test floating point code on Cortex-M hardware.
As part of this patch the link-time-optimisation was disabled because it
wasn't compatible with software FP support. In particular, the linker
could not find the __aeabi_f2d, __aeabi_d2f etc functions even though they
were provided by lib/libm/math.c.
Replaces RUN_TEST=1 definition; now "make test" in qemu-arm directory
will run tests/basics/ and check that they all succeed.
This patch also enables the test on Travis CI.