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/Objects/stringlib/README.txt

@@ -0,0 +1,40 @@
+bits shared by the stringobject and unicodeobject implementations (and
+possibly other modules, in a not too distant future).
+
+the stuff in here is included into relevant places; see the individual
+source files for details.
+
+--------------------------------------------------------------------
+the following defines used by the different modules:
+
+STRINGLIB_CHAR
+
+    the type used to hold a character (char or Py_UNICODE)
+
+STRINGLIB_EMPTY
+
+    a PyObject representing the empty string, only to be used if
+    STRINGLIB_MUTABLE is 0
+
+Py_ssize_t STRINGLIB_LEN(PyObject*)
+
+    returns the length of the given string object (which must be of the
+    right type)
+
+PyObject* STRINGLIB_NEW(STRINGLIB_CHAR*, Py_ssize_t)
+
+    creates a new string object
+
+STRINGLIB_CHAR* STRINGLIB_STR(PyObject*)
+
+    returns the pointer to the character data for the given string
+    object (which must be of the right type)
+
+int STRINGLIB_CHECK_EXACT(PyObject *)
+
+    returns true if the object is an instance of our type, not a subclass
+
+STRINGLIB_MUTABLE
+
+    must be 0 or 1 to tell the cpp macros in stringlib code if the object
+    being operated on is mutable or not