dev-util/numdiff: update EAPI 6 -> 7; fix build with autoconf 2.71

Closes: https://bugs.gentoo.org/806354
Thanks-to: eluancm@gmail.com
Signed-off-by: Sam James <sam@gentoo.org>

dev-util/numdiff/files/numdiff-5.9.0-fix-autoconf-2.71.patch

@@ -0,0 +1,17 @@
+https://bugs.gentoo.org/806354
+--- a/configure.ac
++++ b/configure.ac
+@@ -104,13 +104,6 @@ dnl ------------------------------------
+ dnl Checks for header files
+ dnl --------------------------------------
+ dnl
+-AC_HEADER_STDC
+-if test $ac_cv_header_stdc = yes; then
+- AC_MSG_RESULT(Ok! I have just found them.)
+-else
+-  AC_MSG_ERROR(Cannot find ANSI C header files!)
+-fi
+-
+ AC_HEADER_STDBOOL
+ AC_CHECK_HEADERS(fcntl.h locale.h stddef.h \
+   stdlib.h string.h sys/file.h time.h unistd.h wchar.h wctype.h)

dev-util/numdiff/numdiff-5.9.0.ebuild

@@ -1,7 +1,7 @@
-# Copyright 1999-2020 Gentoo Authors
+# Copyright 1999-2022 Gentoo Authors
 # Distributed under the terms of the GNU General Public License v2
 
-EAPI=6
+EAPI=7
 
 inherit autotools
 
@@ -21,6 +21,7 @@ DEPEND="${RDEPEND}"
 
 PATCHES=(
 	"${FILESDIR}"/${PN}-5.9.0-fix-build-system.patch
+	"${FILESDIR}"/${PN}-5.9.0-fix-autoconf-2.71.patch
 )
 
 src_prepare() {