Rename autoconf auxiliary directory from config to build-aux

Makes the directory name less confusing.

.gitignore

@@ -8,8 +8,8 @@ Makefile.in
 
 # Top dir ignores
 autom4te.cache/
+build-aux/
 build-tree/
-config/
 ABOUT-NLS
 ChangeLog
 INSTALL

configure.ac

@@ -4,7 +4,7 @@ AC_PREREQ(2.60)
 AC_INIT([dpkg], [1.15.5~], [debian-dpkg@lists.debian.org])
 AC_CONFIG_SRCDIR([lib/dpkg/dpkg.h])
 AC_CONFIG_MACRO_DIR([m4])
-AC_CONFIG_AUX_DIR([config])
+AC_CONFIG_AUX_DIR([build-aux])
 
 AC_USE_SYSTEM_EXTENSIONS
 DPKG_ARCHITECTURE