Not all pthreads implementations use an integer type for pthread_t.
As a matter of fact, POSIX has explicitly withdrawn the requirement
that it must be an arithmatic type.
The musl C library uses a `struct __pthread *` which triggered the
warnings. As of this change, sanei_thread.h works around this by
providing two new macros to help keep this issue out of sight. All
backends have been changed to use these macros.
Not all platforms use an integer for pthread_t and so
couldn't compile on those; namely mingw.
This is least riskest version I could come up with. Backends
that do things like "SANE_Pid pid = -1" or "if (pid == -1)" will
need to switch to sanei_thread_set_invalid()
sanei_thread_is_invalid() to be able to compile on mingw.
added functions sanei_thread_sendsig() and sanei_thread_get_status()
changed behaviour of sanei_thread_waitpid(), changed parameters
of sanei_thread_begin()
pthread support, added switch --enable-fork-process which toggles
between the usage of fork and pthread, set the default behaviour to
pthread usage on Darwin
* include/sane/config.h: added the HAVE_LIBPTHRAD stuff
* sanei/sanei_thread.c include/sane/sanei_thread.h: fixed compilation issue
on OS/2, added support for fork too, so that we can use sanei_thread
functions in any case.
* backend/plustek.[ch]: changes due to the sanei_thread-lib work
added linker option -lpthread if pthread.h is found
* include/sane/config.in.h: added HAVE_PTHREAD_H
* sanei/sanei_thread.c include/sane/sanei_thread.h: added pthread_
functions to library, so every backend is able to use either fork or
pthread for its reader-process - see plustek backend for example
* backend/plustek.h backend/plustek.c: added sanei_thread stuff to support
threading on MacOS X
* backend/plustek_pp*: some cleanup
Olaf Meeuwissen