Fixed PATH corruption on Windows for try_compile calls.

On Windows, try_compile calls failed mysteriously due to strange PATH
environment variables. This change fixed that.

CMake/ctkMacroSetPaths.cmake

@@ -26,11 +26,11 @@
 MACRO(ctkMacroSetPaths PATH_LIST)
   FOREACH(p ${PATH_LIST})
     IF(WIN32)
-      SET(ENV{PATH} ${p};$ENV{PATH})
+      SET(ENV{PATH} "${p};$ENV{PATH}")
     ELSEIF(APPLE)
-      SET(ENV{DYLD_LIBRARY_PATH} ${p}:$ENV{DYLD_LIBRARY_PATH})
+      SET(ENV{DYLD_LIBRARY_PATH} "${p}:$ENV{DYLD_LIBRARY_PATH}")
     ELSE()
-      SET(ENV{LD_LIBRARY_PATH} ${p}:$ENV{LD_LIBRARY_PATH})
+      SET(ENV{LD_LIBRARY_PATH} "${p}:$ENV{LD_LIBRARY_PATH}")
     ENDIF()
   ENDFOREACH()
 ENDMACRO()