Use shared config file for functional and util tests

The functional tests and util tests both require a config file that is
generated by ./configure. This commit merges those two config
files into a single configuration file that can be shared by both tests.

The config from config.ini is put into a Namespace object to maintain
the interface with bctest.py. A future commit could change this
interface to use a dictionary instead of a namespace.

test/config.ini.in

@@ -0,0 +1,18 @@
+# Copyright (c) 2013-2016 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+# These environment variables are set by the build process and read by
+# test/functional/test_runner.py and test/util/bitcoin-util-test.py
+
+[environment]
+SRCDIR=@abs_top_srcdir@
+BUILDDIR=@abs_top_builddir@
+EXEEXT=@EXEEXT@
+
+[components]
+# Which components are enabled. These are commented out by `configure` if they were disabled when running config.
+@ENABLE_WALLET_TRUE@ENABLE_WALLET=true
+@BUILD_BITCOIN_UTILS_TRUE@ENABLE_UTILS=true
+@BUILD_BITCOIND_TRUE@ENABLE_BITCOIND=true
+@ENABLE_ZMQ_TRUE@ENABLE_ZMQ=true