USB LISM-PI26xx V2 - portable C/C++ header

usblismpi26.h can be used from C or C++ on Windows and Linux/ARM.

Windows:
  Link against the matching import library, or use the optional
  Cpp_Windows_DynamicLoader files to load the DLL at runtime.

Linux/ARM:
  Link with libusblismpi2664.so (or the matching 32-bit link name).

For multi-device applications use the handle-based functions ending in _ex.

The header also defines the platform-correct LS_ERR_* values. Treat every
non-zero status result as an error and use ls_geterrorstring() for diagnostics.
See docs/ERROR_CODES_2V00.md for native backend pass-through rules.


Endpoint timeout 0 is invalid. A finite endpoint timeout may be shorter than
the interval between complete data blocks because the internal acquisition
thread retries immediately and preserves bytes returned with a timeout.

The portable thread-priority API accepts LS_THREAD_PRIORITY_NORMAL,
LS_THREAD_PRIORITY_ABOVE_NORMAL or LS_THREAD_PRIORITY_HIGH and may be called
while the device is open.
