Merged in david_alessio/nuttx/add-FPU-to-ostest (pull request #562)

Add FPU to xmc4 ostest

* remove +x from makefiles

* preserve .gdbinit across make clean

* add FPU support to ostest on xmc4

* add FPU test to ostest on xmc4

Approved-by: Gregory Nutt <gnutt@nuttx.org>