py_getrandom(): use long type for the syscall() result

Issue #27278. It should fix a conversion warning.

In practice, the Linux kernel doesn't return more than 32 MB per call to the
getrandom() syscall.

Python/random.c

@@ -132,7 +132,7 @@ py_getrandom(void *buffer, Py_ssize_t size, int raise)
      * see https://bugs.python.org/issue26839. To avoid this, use the
      * GRND_NONBLOCK flag. */
     const int flags = GRND_NONBLOCK;
-    int n;
+    long n;
 
     if (!getrandom_works)
         return 0;
@@ -143,7 +143,7 @@ py_getrandom(void *buffer, Py_ssize_t size, int raise)
            to 1024 bytes */
         n = Py_MIN(size, 1024);
 #else
-        n = Py_MIN(size, INT_MAX);
+        n = Py_MIN(size, LONG_MAX);
 #endif
 
         errno = 0;