Revert "[CMake] Fix dependency on codesign steps"

This reverts commit 10506e0.

There are dylibs in lib/swift/macosx/x86_64/ and lib/swift/macosx/, and
with this patch the dylibs in the latter path don't get updated when the
code changes and are stale.

I'm not sure exactly how to correct this patch so let's just try again
when it updates both sets of dylibs.

rdar://28660201

Author: Doug Coleman

cmake/modules/AddSwift.cmake

@@ -1465,25 +1465,17 @@ function(add_swift_library name)
         endif()
 
         set(lipo_target "${name}-${SWIFT_SDK_${sdk}_LIB_SUBDIR}")
-        
-        if("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin" AND SWIFTLIB_SHARED)
-          set(unsigned "-unsigned")
-        endif()
-        
         _add_swift_lipo_target(
             ${sdk}
-            ${lipo_target}${unsigned}
-            "${UNIVERSAL_LIBRARY_NAME}${unsigned}"
+            ${lipo_target}
+            ${UNIVERSAL_LIBRARY_NAME}
             ${THIN_INPUT_TARGETS})
 
         if("${CMAKE_SYSTEM_NAME}" STREQUAL "Darwin" AND SWIFTLIB_SHARED)
           # Ad-hoc sign stdlib dylibs
-          add_custom_command_target(unused_var
-            COMMAND ${CMAKE_COMMAND} -E copy ${UNIVERSAL_LIBRARY_NAME}${unsigned} ${UNIVERSAL_LIBRARY_NAME}
-            COMMAND "codesign" "-f" "-s" "-" "${UNIVERSAL_LIBRARY_NAME}"
-            OUTPUT ${UNIVERSAL_LIBRARY_NAME}
-            DEPENDS ${lipo_target}${unsigned}
-            CUSTOM_TARGET_NAME ${lipo_target})
+          add_custom_command(TARGET "${name}-${SWIFT_SDK_${sdk}_LIB_SUBDIR}"
+                             POST_BUILD
+                             COMMAND "codesign" "-f" "-s" "-" "${UNIVERSAL_LIBRARY_NAME}")
         endif()
 
         # Cache universal libraries for dependency purposes