[Metal] Fix GetFunction of metal runtime (apache#18034)

This PR fixes a bug in `MetalModuleNode::GetFunction`.

The lambda passed to autoreleasepool is supposed to return
nothing. Prior to this PR, it returns a function at an early
exit branch, which may cause the error of `EXC_BREAKPOINT`
in Metal.

Author: MasterJH5574

cmake/Utils/Library.cmake

@@ -16,7 +16,7 @@
 # under the License.
 function(add_dsymutil target_name)
   # running dsymutil on macos to generate debugging symbols for backtraces
-  if(APPLE)
+  if(APPLE AND TVM_FFI_USE_LIBBACKTRACE)
     find_program(DSYMUTIL dsymutil)
     mark_as_advanced(DSYMUTIL)
     add_custom_command(TARGET ${target_name}