CMake: on linux, make boost now always require multithreaded libs, disabling

this was a hack for the precompiled libs in svn. Also bumped minimum version
to 1.48 because that's the first version that contains boost::locale.

CMakeLists.txt

@@ -644,20 +644,15 @@ if(UNIX AND NOT APPLE)
 	if(WITH_BOOST)
 		# uses in build instructions to override include and library variables
 		if(NOT BOOST_CUSTOM)
-			# XXX No more lib dir, is this multithread stuff still needed?
 			if(${WITH_STATIC_LIBS})
 				set(Boost_USE_STATIC_LIBS ON)
 			endif()
-			if(NOT BOOST_ROOT)
-				set(Boost_USE_MULTITHREADED OFF)
-			else()
 			set(Boost_USE_MULTITHREADED ON)
-			endif()
 			set(__boost_packages filesystem regex system thread date_time)
 			if (WITH_INTERNATIONAL)
 				list(APPEND __boost_packages locale)
 			endif()
-			find_package(Boost 1.34 COMPONENTS ${__boost_packages})
+			find_package(Boost 1.48 COMPONENTS ${__boost_packages})
 			if(Boost_USE_STATIC_LIBS AND Boost_USE_ICU)
 				find_package(IcuLinux)
 			endif()