Update link to CMake configure_file

Update http link to CMake 3.0.2 documentation cmake-commands(7) configure_file

Author: Tysun M

include/swift/Config.h.in

@@ -1,5 +1,5 @@
 // This file is processed by CMake.
-// See http://www.cmake.org/cmake/help/v3.0/command/configure_file.html.
+// See https://cmake.org/cmake/help/v3.0/command/configure_file.html.
 
 #ifndef SWIFT_CONFIG_H
 #define SWIFT_CONFIG_H