Fix build and delete superfluous files

- Make Python make formatting pristine
- Add missing `#pragma weak` to Python source
- Fix Clang script flake due to missing directory

test/libc/release/lld.sh

@@ -5,6 +5,7 @@
 # TODO(jart): implement me
 
 if CLANG=$(command -v clang); then
+  mkdir -p o/$MODE/test/libc/release
   $CLANG                                              \
       -o o/$MODE/test/libc/release/smokeclang.com.dbg \
       -Os                                             \