Bug 1655583 - Don't close fds in run-and-prefix.py. r=firefox-build-system-reviewers,rstewart

run-and-prefix.py is used as a wrapper of MAKE in moz-automation.mk, so
that the output is more clearly attributed to what part of the build is
happening, for everything that is post-build (e.g. package, upload,
etc.)

Ever since the switch to python 3, when it re-invokes MAKE, the
jobserver file descriptors would be closed and the sub-make wouldn't be
able to use it.

Differential Revision: https://phabricator.services.mozilla.com/D85051

config/run-and-prefix.py

@@ -21,7 +21,8 @@ args = sys.argv[2:]
 p = subprocess.Popen(args, bufsize=0,
                      stdout=subprocess.PIPE,
                      stderr=subprocess.STDOUT,
-                     stdin=sys.stdin.fileno())
+                     stdin=sys.stdin.fileno(),
+                     close_fds=False)
 
 while True:
     data = p.stdout.readline()