dev-cpp/antlr-cpp: Fix 2.7.7 configure when /bin/sh isn't Bash

Package-Manager: Portage-2.3.6, Repoman-2.3.2

dev-cpp/antlr-cpp/antlr-cpp-2.7.7-r1.ebuild

@@ -1,4 +1,4 @@
-# Copyright 1999-2016 Gentoo Foundation
+# Copyright 1999-2017 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
 
 EAPI=6
@@ -66,7 +66,7 @@ EOF
 }
 
 multilib_src_configure() {
-	econf \
+	CONFIG_SHELL="${BASH}" econf \
 		--disable-csharp \
 		--enable-cxx \
 		--disable-examples \