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/atof.c

@@ -0,0 +1,50 @@
+
+/* Just in case you haven't got an atof() around...
+   This one doesn't check for bad syntax or overflow,
+   and is slow and inaccurate.
+   But it's good enough for the occasional string literal... */
+
+#include "pyconfig.h"
+
+#include <ctype.h>
+
+double atof(char *s)
+{
+    double a = 0.0;
+    int e = 0;
+    int c;
+    while ((c = *s++) != '\0' && isdigit(c)) {
+        a = a*10.0 + (c - '0');
+    }
+    if (c == '.') {
+        while ((c = *s++) != '\0' && isdigit(c)) {
+            a = a*10.0 + (c - '0');
+            e = e-1;
+        }
+    }
+    if (c == 'e' || c == 'E') {
+        int sign = 1;
+        int i = 0;
+        c = *s++;
+        if (c == '+')
+            c = *s++;
+        else if (c == '-') {
+            c = *s++;
+            sign = -1;
+        }
+        while (isdigit(c)) {
+            i = i*10 + (c - '0');
+            c = *s++;
+        }
+        e += i*sign;
+    }
+    while (e > 0) {
+        a *= 10.0;
+        e--;
+    }
+    while (e < 0) {
+        a *= 0.1;
+        e++;
+    }
+    return a;
+}