Upgraded autoconf to 2.71

Makefile

 all:
-	tar xf autoconf-2.69.tar.xz
-	patch -Np1 -d autoconf-2.69 < autoconf-2.69-tests.patch
-	cd autoconf-2.69 && ./configure --build=$(CLFS_TARGET) --prefix=/usr
-	$(MAKE) -C autoconf-2.69
-	$(MAKE) -C autoconf-2.69 install
+	tar xf autoconf-2.71.tar.xz
+	cd autoconf-2.71 && ./configure --build=$(CLFS_TARGET) --prefix=/usr
+	$(MAKE) -C autoconf-2.71
+	$(MAKE) -C autoconf-2.71 install
 
 tests:
-# The test suite is currently broken by bash-5 and libtool-2.4.3
-#	if [[ ! "$(BUILD_OPTIONS)" =~ no-tests ]] ; then \
-#	    $(MAKE) -C autoconf-2.69 check VERBOSE=yes PERL_USE_UNSAFE_INC=1 ; \
-#	fi
-	rm -rf autoconf-2.69
+	if [[ ! "$(BUILD_OPTIONS)" =~ no-tests ]] ; then \
+	    $(MAKE) -C autoconf-2.71 check VERBOSE=yes PERL_USE_UNSAFE_INC=1 ; \
+	fi
+	rm -rf autoconf-2.71

autoconf-2.69-tests.patch

-diff -uNr autoconf-2.69/bin/autoscan.in autoconf-2.69-tests/bin/autoscan.in
---- autoconf-2.69/bin/autoscan.in	2012-04-25 02:37:26.000000000 +0000
-+++ autoconf-2.69-tests/bin/autoscan.in	2017-12-11 16:10:24.212523193 +0000
-@@ -358,7 +358,7 @@
-     {
-       # Strip out comments and variable references.
-       s/#.*//;
--      s/\${[^\}]*}//g;
-+      s/\$\{[^\}]*}//g;
-       s/@[^@]*@//g;
- 
-       # Tokens in the code.
-diff -uNr autoconf-2.69/tests/foreign.at autoconf-2.69-tests/tests/foreign.at
---- autoconf-2.69/tests/foreign.at	2012-03-07 17:35:26.000000000 +0000
-+++ autoconf-2.69-tests/tests/foreign.at	2017-12-11 16:15:55.815318542 +0000
-@@ -57,7 +57,7 @@
- # Make sure at-path contains something valid, and let the test suite
- # display it when verbose.  And fail, skipping would too easily hide
- # problems.
--AT_CHECK([sed -n ["s,^.*\`\\(/[^']*\\)'.*,\\1,p"] stdout], [0], [stdout])
-+AT_CHECK([sed -n ["s,^[^']*[\`']\\(/[^']*\\)'.*,\\1,p"] stdout], [0], [stdout])
- AT_CHECK([test -f "`sed -n 1p stdout`"])
- 
- # Older libtoolize installed everything but install-sh...