Revert "Revert "rpc-tests: re-enable rpc-tests for Windows""

This reverts commit 7fd5d4e30e.

We need to un-revert this before pulling in
https://github.com/bitcoin/bitcoin/pull/6616

qa/pull-tester/rpc-tests.sh

@@ -8,11 +8,6 @@ CURDIR=$(cd $(dirname "$0"); pwd)
 export BITCOINCLI=${BUILDDIR}/qa/pull-tester/run-bitcoin-cli
 export BITCOIND=${REAL_BITCOIND}
 
-if [ "x${EXEEXT}" = "x.exe" ]; then
-  echo "Win tests currently disabled"
-  exit 0
-fi
-
 #Run the tests
 
 testScripts=(