codec/rfx: removed unnecessary WaitForSingleObject

The WaitForSingleObject call on TilePool's event is called with a zero time-out
interval and the event is a manual reset event ... thus no locking or waiting
is involved anyways and Queue_Dequeue may very well return NULL independently
of calling WaitForSingleObject which is already correctly handled.
Added proper find_feature check for JPEG library.
winpr: improve and fix locking for data structures

- Improved/completed(almost) winpr's critical section implementation
- Replaced WaitForSingleObject locking with critical sections

Note:
WaitForSingleObject should _never_ be used for granular low-contention
locks as it _always_ enters the kernel.

Just replacing WaitForSingleObject locking in Bufferpool with
EnterCriticalSection boosts the multithreaded rfx decoder
performance by almost 400% on win32.
Added proper CMake checks for libraries linked with urbdrc
Now using libraries detected by CMake for linking against libusb.
Fixed linking with libusb, now linking against correct library.
Added libusb detection CMake script.
Merge pull request #1388 from nfedera/fix-2013-08-02-01

winpr: improve and fix locking for data structures
Merge pull request #1389 from akallabeth/urbdrc_cmake_fixes

Urbdrc cmake fixes
Merge pull request #1386 from akallabeth/master

Added proper find_feature check for JPEG library.
Merge pull request #1379 from nfedera/fix-2013-07-30-01

codec/rfx: removed unnecessary WaitForSingleObject
libfreerdp-core/fastpath: fix memory leak when sending large packet.