Xcode/thumbnailer: rebuild error due to rpath

Fix duplicate rpath error on rebuild by using CMake target
property.

Pull Request: https://projects.blender.org/blender/blender/pulls/134527

CMakeLists.txt

@@ -219,8 +219,8 @@ intended for use by file-managers to extract PNG images from `.blend` files."
   )
 elseif(APPLE)
   option(WITH_BLENDER_THUMBNAILER "\
-Build \"blender-thumbnailer.appex\" extension for macOS Finder/ QuickLook to support viewing \
-thumbnails from `.blend` files."
+Build \"blender-thumbnailer.appex\" extension for Finder/ QuickLook thumbnail \
+support for blend files."
     ON
   )
 endif()

source/blender/blendthumb/CMakeLists.txt

@@ -58,13 +58,14 @@ elseif(APPLE)
     "-e _NSExtensionMain"
     "-framework QuickLookThumbnailing"
   )
-  # CMake needs the target defined in the same file as add_custom_command.
   # The RPATH here points to the main Blender Resources/lib directory.
   # Avoid duplicating the large `dylibs` (~300MB).
-  add_custom_command(
-    TARGET blender-thumbnailer POST_BUILD
-    COMMAND install_name_tool -add_rpath @loader_path/../../../../Resources/lib $<TARGET_FILE:blender-thumbnailer>
+  set_target_properties(blender-thumbnailer PROPERTIES
+    INSTALL_RPATH "@loader_path/../../../../Resources/lib"
+    # Prevent Xcode from overwriting the signature.
+    XCODE_ATTRIBUTE_CODE_SIGN_IDENTITY ""
   )
+  # CMake needs the target defined in the same file as add_custom_command.
   # It needs to be code-signed (ad-hoc in this case)
   # even on developer machine to generate thumbnails.
   # Command taken from XCode build process.

source/blender/blendthumb/src/thumbnail_provider.mm

@@ -43,7 +43,7 @@
  *
  * LLDB/ Xcode etc., debuggers can be used to get extra logs than CLI invocation but breakpoints
  * still are a pain point. /usr/bin/qlmanage is the target executable. Other args to qlmanage
- * follow.
+ * follow. lldb qlmanage --  -t -x a.blend
  *
  * # Troubleshooting
  * - The appex shouldn't have any quarantine flag.
@@ -62,7 +62,7 @@
  * - The code cannot attempt to do anything outside sandbox like writing to blend.
  *
  * # Triggering a thumbnail
- * - qlmanage -t -s 512 -o /tmp/ /path/to/file.blend
+ * - qlmanage -t -x /path/to/file.blend
  *
  * # External resources
  * https://developer.apple.com/library/archive/documentation/UserExperience/Conceptual/Quicklook_Programming_Guide/Introduction/Introduction.html#//apple_ref/doc/uid/TP40005020-CH1-SW1