Previous to this patch the qemu-arm tests were compiled with is_relp=true
meaning that the __repl_print__ function was called for all lines of code
in the outer scope. This is not the right behaviour for scripts that are
executed as though they were a file (eg tests).
With this fix the micropython/heapalloc_str.py test now works so it is
removed from the test blacklist.
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.
