configure.ac: Increase minimum required version to 2.64

README.checkout

@@ -8,7 +8,7 @@ Compiling From Repository Sources
    libiconv, libpsl, libpcre, pkg-config, libmetalink and GnuPG are not
    absolutely required):
 
-     * [20]autoconf (currently, GNU Wget requires version 2.61). This is
+     * [20]autoconf (currently, GNU Wget requires version 2.64). This is
        needed to generate the configure script from configure.in. This is
        not required when building from a tarball distribution; only when
        building from repository sources.

bootstrap.conf

@@ -140,7 +140,7 @@ gnulib_extra_files="
 
 # Build prerequisites
 buildreq="\
-autoconf   2.62
+autoconf   2.64
 automake   1.11.1
 autopoint  -
 gettext    0.17

configure.ac

@@ -33,7 +33,7 @@ dnl
 AC_INIT([wget],
         m4_esyscmd([build-aux/git-version-gen .tarball-version]),
 	[bug-wget@gnu.org])
-AC_PREREQ(2.63)
+AC_PREREQ(2.64)
 
 dnl
 dnl What version of Wget are we building?