contrib(UWP): revert to gnutls 3.4.17

Until API supported substitutes for certain crypto functions can be
found, reverting to v3.4.17 will allow passage into the store.
This patch also reverts nettle to an earlier commit.

Change-Id: I5d9c2341113ccd3f99512ffa922e95dc7a5b89b6

contrib/src/gnutls/fetch_and_patch.bat

 set BUILD=%SRC%..\build
 
-set GNUTLS_VERSION=gnutls_3_5_10
+set GNUTLS_VERSION=f2d0ade53ff644da55244aed79d05eca78d11a2f
 set GNUTLS_URL=https://github.com/ShiftMediaProject/gnutls/archive/%GNUTLS_VERSION%.tar.gz
 
 mkdir %BUILD%

contrib/src/nettle/fetch_and_patch.bat

 set BUILD=%SRC%..\build
 
-set NETTLE_VERSION=nettle_3.3_release_20161001
+set NETTLE_VERSION=4e0b2723b76d4163fa37b2b456d41534154ec97c
 set NETTLE_URL=https://github.com/ShiftMediaProject/nettle/archive/%NETTLE_VERSION%.tar.gz
 
 mkdir %BUILD%