scripts: size_report: Fix reporting on Windows

Certain symbols do not contain a valid path, instead showing
`<built-in>` in the filename attribute. This leads to the resolve() call
failing on Windows, since the `<>` characters are not allowed in
filenames there. Fix this by catching the exception and skipping the
call in that case.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>

scripts/footprint/size_report

@@ -221,7 +221,13 @@ def get_die_filename(die, lineprog):
         path = output.joinpath(path)
 
     # Change path to relative to Zephyr base
-    path = path.resolve()
+    try:
+        path = path.resolve()
+    except OSError as e:
+        if '<built-in>' in str(path):
+            # This is expected, built-ins can't be resolved
+            return path
+        raise e
     try:
         new_path = path.relative_to(zephyrbase)
         path = new_path