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/util/bitcoin-util-test.py

@@ -20,7 +20,7 @@ if __name__ == '__main__':
     import bctest
 
     config = configparser.ConfigParser()
-    config.read_file(open(os.path.dirname(__file__) + "/config.ini"))
+    config.read_file(open(os.path.dirname(__file__) + "/../config.ini"))
 
     buildenv = argparse.Namespace(exeext=config["environment"]["EXEEXT"],
                                   SRCDIR=config["environment"]["SRCDIR"],

test/util/config.ini.in

@@ -1,11 +0,0 @@
-# Copyright (c) 2013-2017 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/util/bitcoin-util-test.py
-
-[environment]
-SRCDIR=@abs_top_srcdir@
-BUILDDIR=@abs_top_builddir@
-EXEEXT=@EXEEXT@