Prior to this change, the libusbx52 Makefile was manually specifying the
pthread flags to indicate that the linker needed to link against the
pthread libraries.
This change moves the pthread detection logic out to configure.ac, and
updates the flags in libusbx52 Makefile to use the pthread compiler.
The stub libusb library used for testing writes the control request to a
dump file. By default, this file is block-buffered, and on a typical
Linux system, it waits until it receives about a page worth of data
before flushing it to disk. This results in a delay in monitoring
packets when running a debug program.
This change makes the file line-buffered instead, which results in the
debug output for every single packet getting flushed to disk without
having to wait for a full page of data.
With the release of libusb 1.0.22, `libusb_set_debug` has been
deprecated and replaced by `libusb_set_option`. This function is a new
generic API to add additional functionality in the future without having
to introduce new functions.
This change checks for `LIBUSB_API_VERSION` of at least `0x01000106`,
which is the version corresponding to 1.0.22, and if it matches, it
replaces the calls to `libusb_set_debug` with equivalent calls to
`libusb_set_option`.
nirenjan