setup.py: switch to out of tree builds.

libusb 1.0.25 added support for out of tree builds.

setup.py

@@ -86,12 +86,10 @@ def run(self):
         build_lib = ROOT_DIR / Path(build_py.get_package_dir(PACKAGE_NAME)).parent
     else:
         build_lib = Path(os.path.abspath(self.build_lib))
-#     build_temp = Path(os.path.abspath(self.build_temp))
 
-    # Build in-tree for the time being. libusb commit 1001cb5 adds support for out of tree builds, but
-    # this is not yet supported in an existing release. Once libusb version 1.0.25 is released, we can
-    # build out of tree.
-    build_temp = LIBUSB_DIR
+    # Build out of tree. Requires libusb commit 1001cb5 which adds support for out of tree builds, present
+    # in libusb 1.0.25 and later.
+    build_temp = Path(os.path.abspath(self.build_temp))
 
     print(f"build_temp = {build_temp}")
     print(f"build_lib = {build_lib}")