drivers/libusb_helper: introduce oocd_libusb_dev_mem_alloc() helper
On some systems (at least Windows/CYGWIN and macOS) libusb_dev_mem_alloc()
simply returns NULL.
Use the result of the very first libusb_dev_mem_alloc() call to decide
if the underlining system supports dev mem allocation or we should
fall-back to plain heap malloc().
From the decision time on, keep using the selected type of memory allocator
and deallocator.
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Change-Id: Ia1f0965cea44b4bb6d936b02ec43f5a16a46f080
Reviewed-on: https://review.openocd.org/c/openocd/+/8059
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>