Remove/disable broken code for loading the encoder library from a macos bundle

This refers to a file "bundlewelsenc.h" which doesn't even
exist in the project at the moment.

The corresponding bundle loading code is not called at all
in the decoder console tool.
Remove unused files about macos bundle loading from the console tools
Remove an exclude of an nonexistent file
Only build the thread code if multithreading is enabled

This allows including the source file in the build even if
multithreading isn't desired.
Move the WelsThreadLib files to the common directory/library

This simplifies building the thread library code via the
makefile based build system.
Remove unused typedefs
Merge pull request #180 from mstorsjo/remove-disabled-bundle-loading

Remove disabled/broken/unused code for bundle loading in the console tools
Merge pull request #182 from mstorsjo/move-threadlib

Move the WelsThreadLib files to the common directory/library
Merge pull request #183 from mstorsjo/remove-unused-typedef

Remove unused typedefs
Don't include the headers for dynamically loading the VP library if NO_DYNAMIC_VP is defined

bundleloader.h, which is included if MACOS is defined, defines
inline functions that reference bundle loading system functions,
which requires linking to the core foundation framework.

Avoid requiring linking to extra libraries/frameworks if
NO_DYNAMIC_VP is defined.
Define MACOS when building for OS X

The library uses this define to enable OS X specific functionality
in general, even if none of those snippets actually have been
strictly required so far.
Merge pull request #185 from mstorsjo/macos-define

Define MACOS when building for OS X
Merge remote-tracking branch 'upstream/master' into travis.osx