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/Modules/_math.h

@@ -0,0 +1,41 @@
+double _Py_acosh(double x);
+double _Py_asinh(double x);
+double _Py_atanh(double x);
+double _Py_expm1(double x);
+double _Py_log1p(double x);
+
+#ifdef HAVE_ACOSH
+#define m_acosh acosh
+#else
+/* if the system doesn't have acosh, use the substitute
+   function defined in Modules/_math.c. */
+#define m_acosh _Py_acosh
+#endif
+
+#ifdef HAVE_ASINH
+#define m_asinh asinh
+#else
+/* if the system doesn't have asinh, use the substitute
+   function defined in Modules/_math.c. */
+#define m_asinh _Py_asinh
+#endif
+
+#ifdef HAVE_ATANH
+#define m_atanh atanh
+#else
+/* if the system doesn't have atanh, use the substitute
+   function defined in Modules/_math.c. */
+#define m_atanh _Py_atanh
+#endif
+
+#ifdef HAVE_EXPM1
+#define m_expm1 expm1
+#else
+/* if the system doesn't have expm1, use the substitute
+   function defined in Modules/_math.c. */
+#define m_expm1 _Py_expm1
+#endif
+
+/* Use the substitute from _math.c on all platforms:
+   it includes workarounds for buggy handling of zeros. */
+#define m_log1p _Py_log1p