layout: restructure into src/ tests/ android/ scripts/ tools/

- extension/src/{port,platform,codepage} -> src/; native_render -> src/host
  (+ dxt, shaders/); libgr2 -> src/gr2; extension/third_party -> third_party
- extension/tests -> tests/port, libgr2/tests -> tests/gr2
- android-native -> android (build.sh, push-client.sh moved in)
- script -> scripts; tools/40250 -> tools/server; oracle -> tools/granny-oracle;
  perf tools -> tools/perf
- all build trees under build/ (native, release, android, port-gate)
- xrender:: CMake aliases -> mt::; port-map ledger impl paths rewritten

No code changes. ctest 15/15, port_gate macos+android PASS, port_map check 0 errors.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

third_party/cpython-2.7.18/Lib/email/mime/multipart.py

@@ -0,0 +1,47 @@
+# Copyright (C) 2002-2006 Python Software Foundation
+# Author: Barry Warsaw
+# Contact: email-sig@python.org
+
+"""Base class for MIME multipart/* type messages."""
+
+__all__ = ['MIMEMultipart']
+
+from email.mime.base import MIMEBase
+
+
+
+class MIMEMultipart(MIMEBase):
+    """Base class for MIME multipart/* type messages."""
+
+    def __init__(self, _subtype='mixed', boundary=None, _subparts=None,
+                 **_params):
+        """Creates a multipart/* type message.
+
+        By default, creates a multipart/mixed message, with proper
+        Content-Type and MIME-Version headers.
+
+        _subtype is the subtype of the multipart content type, defaulting to
+        `mixed'.
+
+        boundary is the multipart boundary string.  By default it is
+        calculated as needed.
+
+        _subparts is a sequence of initial subparts for the payload.  It
+        must be an iterable object, such as a list.  You can always
+        attach new subparts to the message by using the attach() method.
+
+        Additional parameters for the Content-Type header are taken from the
+        keyword arguments (or passed into the _params argument).
+        """
+        MIMEBase.__init__(self, 'multipart', _subtype, **_params)
+
+        # Initialise _payload to an empty list as the Message superclass's
+        # implementation of is_multipart assumes that _payload is a list for
+        # multipart messages.
+        self._payload = []
+
+        if _subparts:
+            for p in _subparts:
+                self.attach(p)
+        if boundary:
+            self.set_boundary(boundary)