Use native CMakeLists.txt for portaudio

The same story as libexpat's one--native CMakeLists.txt does its job better
than the proxy. Also it seems to be able to otionally build with ASIO support
on Windows. And it successfully builds on linux, freebsd and osx.

src/CMakeLists.txt

@@ -493,13 +493,13 @@ add_executable( Audacity ${SOURCE} )
 message( STATUS "link directory is: ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/Debug" )
 message( STATUS "wxWidgets libraries in: ${wxWidgets_LIBRARIES}" )
 
-target_link_libraries(Audacity 
+target_link_libraries(Audacity
 ${wxWidgets_LIBRARIES}
-expat.lib
-FileDialog.lib
-libsndfile.lib
-libsoxr.lib
-portaudio-v19.lib
+expat
+FileDialog
+libsndfile
+libsoxr
+portaudio_static
 )
 if(MSVC)
     set_property(TARGET Audacity APPEND PROPERTY LINK_FLAGS "/SUBSYSTEM:WINDOWS /LIBPATH:${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/Debug")
@@ -534,4 +534,4 @@ if (TARGET ${_unityTargetName})
 	message(STATUS "Audacity unity target: ${_unityTargetName}")
 endif()
 
-]]#
+]]#