Revert "Re-add..."

This reverts commit b1faebae4a.

ext/libpqxx-7.7.3/tools/m4esc.py

@@ -1,70 +0,0 @@
-#! /usr/bin/env python3
-
-"""M4-quote text, for use as a literal in configure.ac.
-
-Produces M4 "code" which evaluates to the input text.
-
-It's not easy to read plain text from an input file in M4, without having it
-expanded as M4.  Sometimes all we want is literal text!
-"""
-from __future__ import (
-    absolute_import,
-    print_function,
-    unicode_literals,
-    )
-
-from argparse import ArgumentParser
-from sys import (
-    stdin,
-    stdout,
-    )
-
-
-def parse_args():
-    parser = ArgumentParser(description=__doc__)
-    parser.add_argument(
-        '--open', '-a', default='[[', help="Current open-quote symbol.")
-    parser.add_argument(
-        '--close', '-b', default=']]', help="Current close-quote symbol.")
-    parser.add_argument(
-        '--input', '-i', default='-', help="Input file, or '-' for stdin.")
-    parser.add_argument(
-        '--output', '-o', default='-', help="Output file, or '-' for stdout.")
-    return parser.parse_args()
-
-
-def open_input(in_file):
-    if in_file == '-':
-        return stdin
-    else:
-        return open(in_file)
-
-
-def open_output(out_file):
-    if out_file == '-':
-        return stdout
-    else:
-        return open(out_file, 'w')
-
-
-def escape(line):
-    return (
-        line
-        .replace('[', '@<:@')
-        .replace(']', '@:>@')
-        .replace('#', '@%:@')
-        .replace('$', '@S|@')
-    )
-
-
-def main(args):
-    with open_input(args.input) as istr, open_output(args.output) as ostr:
-        ostr.write(args.open)
-        for line in istr:
-            ostr.write(escape(line))
-            ostr.write('\n')
-        ostr.write(args.close)
-
-
-if __name__ == '__main__':
-    main(parse_args())