Implemented and tested some utility functions

The subject is the test program for the GPS.

This was actually wrong, the Antenova M10478 GPS module doesn't need a double
ON_OFF pin pulse, it just needs an ~150ms delay from the time its EXT_RST pin
is asserted to the time it can dump out data.

What was happening before is that we didn't have a delay in the gps_init
function before sending the on_off pulse, and this meant that the pulse was
missed by the module, which never turned on.

The added delay fixes this issue and we now need only a single pulse.

The problem was that one needs to STATICALLY allocate the buffer
that sends the data to the GPS. In this case, making the rxbuf
static inside gps/main.c fixed the problem.

For safety, the buffer inside usbdbg_puts() was also made static, and aligned
to a word (32-bit) boundary, as advised by the SiLabs USB device library.

usbled host-side s/w controls blinking the LEDs
EFM32 code in usbdcdc

Conflicts:
	sw/os-comparison/freertos_blink/armgcc/Makefile

Signed-off-by: Theodor Stana <t.stana@cern.ch>