Fix mpv not working out of the box in win32 source build

Regressed in 711c28e1a5

build/runner/src/build.rs

@@ -27,7 +27,7 @@ pub fn run_build(args: BuildArgs) {
 
     let path = if cfg!(windows) {
         format!(
-            "out\\bin;out\\extracted\\node;node_modules\\.bin;out\\extracted\\win_amd64_audio;{};\\msys64\\usr\\bin",
+            "out\\bin;out\\extracted\\node;node_modules\\.bin;{};\\msys64\\usr\\bin",
             env::var("PATH").unwrap()
         )
     } else {

tools/run.py

@@ -5,6 +5,8 @@ import os
 import sys
 
 sys.path.extend(["pylib", "qt", "out/pylib", "out/qt"])
+if sys.platform == "win32":
+    os.environ["PATH"] += ";out\\extracted\\win_amd64_audio"
 
 import aqt