LibTargets.mk, tools/Config.mk:  Drop executable bit on installed libraries. The rules to install libraries under lib/ were modified to use mode 0644 instead of the default 0755.

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>

boardctl(): Add a new non-standard OS interface.  This is similar to a driver IOCTL call.  But this is an IOCTL call directly on the board logic.  This function will eventually replace all of the ad hoc OS interfaces that are current used to perform application specific intialiation and application driver test confifuration.  It essentially formalizes and institutionalizes these rogue interface in to at least a single crazy call.

Add logic that will permit us to build user libraries with different CFLAGS than kernel code.  This is needed because we need the -fno-common option when building ELF code to prevent SHN_COMMON relocations