pythongh-108223: Add [NOGIL] marker to sys.version

If Python is configured with --disable-gil, add " [NOGIL]" suffix to
sys.version. It should help users to check if they are running a
regular Python build with a GIL, or a custom Python build with the
new experimental no GIL.

sys.version is commonly requested in bug reports: knowing if Python
was configured with --disable-gil should ease debug.

Example on Linux with --disable-gil:

    $ ./python -VV
    Python 3.13.0a0 (heads/main-dirty:d63972e289, Aug 21 2023,
    21:43:45) [GCC 13.2.1 20230728 (Red Hat 13.2.1-1)] [NOGIL]

Python/getversion.c

@@ -6,16 +6,21 @@
 #include "patchlevel.h"
 
 static int initialized = 0;
-static char version[250];
+static char version[258];
 
 void _Py_InitVersion(void)
 {
     if (initialized) {
         return;
     }
     initialized = 1;
-    PyOS_snprintf(version, sizeof(version), "%.80s (%.80s) %.80s",
-                  PY_VERSION, Py_GetBuildInfo(), Py_GetCompiler());
+#ifdef Py_NOGIL
+    const char *gil = " [NOGIL]";  // 8 characters
+#else
+    const char *gil = "";
+#endif
+    PyOS_snprintf(version, sizeof(version), "%.80s (%.80s) %.80s%s",
+                  PY_VERSION, Py_GetBuildInfo(), Py_GetCompiler(), gil);
 }
 
 const char *