make compilation OS and platform independent

add check for PC platform and use windows-style paths there
add check for 64 bit platforms (not windows 64 bit only) and set
ARCH=x64 accordingly

suppress the output of ARCH and BLADERF_PATH
adapt to API change in bladerf firmware version

the interface of bladerf_version was changed recently, reflect this
change in the matlab bladerf_fw_version.c file