run-tests: use the common test path on Windows and Java

The alternate one did not run in the test directory and controlling
the jobs execution with threads instead of process made it harder
to fix.

tests/run-tests.py

@@ -642,14 +642,6 b' def run(cmd, wd, options, replacements):'
         ret = proc.wait()
         return (ret, None)
 
-    if os.name == 'nt' or sys.platform.startswith('java'):
-        tochild, fromchild = os.popen4(cmd)
-        tochild.close()
-        output = fromchild.read()
-        ret = fromchild.close()
-        if ret is None:
-            ret = 0
-    else:
         proc = Popen4(cmd, wd, options.timeout)
         def cleanup():
             try: