python*: upstream patches to fix with glibc-2.25

https://bugs.python.org/issue29157
The 3.6 release already contains the fix (from 3.5);
the branches in-between are claimed to be unaffected.
/cc #22874.

pkgs/development/interpreters/python/cpython/2.7/default.nix

@@ -66,6 +66,8 @@ let
       # libuuid, slowing down program startup a lot).
       ./no-ldconfig.patch
 
+      ./glibc-2.25-enosys.patch
+
     ] ++ optionals stdenv.isCygwin [
       ./2.5.2-ctypes-util-find_library.patch
       ./2.5.2-tkinter-x11.patch

pkgs/development/interpreters/python/cpython/2.7/glibc-2.25-enosys.patch

@@ -0,0 +1,15 @@
+https://bugs.python.org/issue29157
+https://github.com/python/cpython/commit/01bdbad3e951
+diff --git a/Python/random.c b/Python/random.c
+index 2f83b5d..0b775ec 100644
+--- a/Python/random.c
++++ b/Python/random.c
+@@ -98,7 +98,7 @@ win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise)
+ 
+ /* Issue #25003: Don't use getentropy() on Solaris (available since
+  * Solaris 11.3), it is blocking whereas os.urandom() should not block. */
+-#elif defined(HAVE_GETENTROPY) && !defined(sun)
++#elif defined(HAVE_GETENTROPY) && !defined(sun) && !defined(linux)
+ #define PY_GETENTROPY 1
+ 
+ /* Fill buffer with size pseudo-random bytes generated by getentropy().