mscoree/tests: Use wait_child_process for csc process.

dlls/mscoree/tests/comtest.c

@@ -94,7 +94,7 @@ static BOOL compile_cs_to_dll(char *source_path, char *dest_path)
     ret = CreateProcessA(path_csc, cmdline, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
     ok(ret, "Could not create process: %lu\n", GetLastError());
 
-    WaitForSingleObject(pi.hProcess, 5000);
+    wait_child_process(pi.hProcess);
     CloseHandle(pi.hThread);
     CloseHandle(pi.hProcess);