Fix a typo and add missing commas.

Also, delete a blank line at the end of the file and
use /* */ for comments consistently.

Closes #1071

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>

Closes #830

Found via `codespell -q 3`

Closes #1015

Add another approach for connecting USB devices on Android.

References #830
Closes #996

Fixes #31

See #143 and #596 for solutions to the whole build system.

Closes #971

There are certain games played in the examples and tests source to
account for differences in build environments and target platforms. This
can be simplified by including config.h and using the definitions there.

To that end, move the printf function attribute definition from
libusbi.h to config.h and leverage it where it is used in the examples
and tests.

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

Commit f69548c3b3 ("examples: Enable all examples to build on all
platforms") modified dpfp and sam3u_benchmark to be buildable on any
platform, however there were some oversights and regressions introduced
for Android and Xcode.

Update the Android and Xcode build files to account for the removal of
dpfp_threaded.c as well as the inclusion of config.h from examples
and/or tests source.

Additionally switch the threaded version of dpfp to use sem_open()
instead of sem_init() as the latter is in fact deprecated on MacOS.

Closes #808

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

The split between events and threads abstractions is unnecessary.
Simplify the library by merging the two into a "platform" abstraction.
The only meaningful change is that Cygwin builds will no longer use the
POSIX threads abstraction but will instead use the native Windows one.

The downside to doing this is that the dpfp_threaded example program
will no longer be available on Cygwin builds. This should be fine, and
future work will make dpfp_threaded available for all forms of Windows
build systems.

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

The way in which system handles or resources are represented differs
greatly between Unix-like operating systems and Windows. Ever since
Windows support was added to libusb, Windows been emulating principles
of Unix-like operating systems such as file descriptors and poll().

This commit introduces an abstraction layer that completely removes the
need to perform any emulation. Fundamentally there are three things that
each platform provides to libusb:

  1) A signallable event
  2) A timer (not required, but useful)
  3) A means to wait for event sources such as the above to be triggered

The POSIX abstraction for Unix-like operating systems uses file
descriptors as the "handles" to the underlying system resources. The
signallable event is implemented using a pipe, the timer as a timerfd
(where supported) and the poll() system call is used to wait for events.

The Windows abstraction uses native HANDLEs as the "handles" to the
underlying system resources. The signallable event is implemented using
a manual-reset event, the timer as a manual-reset waitable timer, and
the WaitForMultipleObjects() system call is used to wait for events.

Closes #252

Signed-off-by: Chris Dickens <christopher.a.dickens@gmail.com>

A command line option is not correct.
Fix by spelling the option correctly.

BEFORE

[x86] Compile        : xusb <= xusb.c
warning: unknown warning option '-Werror=unintialized'; did you mean '-Werror=uninitialized'? [-Wunknown-warning-option]

AFTER

[x86] Compile        : xusb <= xusb.c
[x86] Executable     : xusb
[x86] Install        : xusb => libs/x86/xusb