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/Python/pyfpe.c

@@ -0,0 +1,23 @@
+#include "pyconfig.h"
+#include "pyfpe.h"
+/* 
+ * The signal handler for SIGFPE is actually declared in an external
+ * module fpectl, or as preferred by the user.  These variable
+ * definitions are required in order to compile Python without
+ * getting missing externals, but to actually handle SIGFPE requires
+ * defining a handler and enabling generation of SIGFPE.
+ */
+
+#ifdef WANT_SIGFPE_HANDLER
+jmp_buf PyFPE_jbuf;
+int PyFPE_counter = 0;
+#endif
+
+/* Have this outside the above #ifdef, since some picky ANSI compilers issue a 
+   warning when compiling an empty file. */
+
+double
+PyFPE_dummy(void *dummy)
+{
+	return 1.0;
+}