OSX/cmake: use CMAKE_XCODE_ATTRIBUTE rather than CMAKE_OSX_SYSROOT and set min...

OSX/cmake: use CMAKE_XCODE_ATTRIBUTE rather than CMAKE_OSX_SYSROOT and set min deployment target to 10.6 now

CMakeLists.txt

@@ -359,10 +359,13 @@ if(APPLE)
 		message(STATUS "OSX_SYSROOT_PREFIX: " ${OSX_SYSROOT_PREFIX})
 		set(OSX_DEVELOPER_PREFIX /Developer/SDKs/MacOSX${OSX_SYSTEM}.sdk) # use guaranteed existing sdk
 		set(CMAKE_OSX_SYSROOT ${OSX_SYSROOT_PREFIX}/${OSX_DEVELOPER_PREFIX} CACHE PATH "" FORCE)
+        if(${CMAKE_GENERATOR} MATCHES "Xcode")
+            set(CMAKE_XCODE_ATTRIBUTE_SDKROOT macosx${OSX_SYSTEM}) # to silence sdk not found warning, just overrides CMAKE_OSX_SYSROOT
+        endif()
 	endif()
 	
 	if(NOT CMAKE_OSX_DEPLOYMENT_TARGET)
-		set(CMAKE_OSX_DEPLOYMENT_TARGET "10.5" CACHE STRING "" FORCE) # 10.5 is our min. target, if you use higher sdk, weak linking happens
+		set(CMAKE_OSX_DEPLOYMENT_TARGET "10.6" CACHE STRING "" FORCE) # 10.6 is our min. target, if you use higher sdk, weak linking happens
 	endif()
 	
 	if(NOT ${CMAKE_GENERATOR} MATCHES "Xcode")
@@ -1472,7 +1475,7 @@ elseif(WIN32)
 elseif(APPLE)
 
 	if(${CMAKE_OSX_DEPLOYMENT_TARGET} STREQUAL "10.5" OR ${CMAKE_OSX_DEPLOYMENT_TARGET} STRGREATER "10.5")
-		set(WITH_LIBS10.5 ON CACHE BOOL "Use 10.5 libs" FORCE) # valid also for 10.6/10.7
+		set(WITH_LIBS10.5 ON CACHE BOOL "Use 10.5 libs" FORCE) # valid also for 10.6/7/8/9
 	endif()
 
 	if(WITH_LIBS10.5)