https://sources.debian.org/patches/libinklevel/0.9.3-3/0001-configure.ac-fix-ftbfs-with-autoconf2.70.patch/
https://bugs.gentoo.org/750173

From: Boyuan Yang <byang@debian.org>
Date: Sat, 16 Jan 2021 11:03:56 -0500
Subject: configure.ac: fix ftbfs with autoconf2.70

Applied-Upstream: email, yes
--- a/configure.ac
+++ b/configure.ac
@@ -12,7 +12,7 @@ ABI_VERSION=5:0:0
 
 dnl no more configuration after this line
 
-AC_CONFIG_SRCDIR(libinklevel.c)
+AC_CONFIG_SRCDIR([libinklevel.c])
 
 ## Determine hostname & OS
 ## AC_CANONICAL_HOST
@@ -77,9 +77,9 @@ AC_CHECK_HEADERS([ifaddrs.h])
 
 ## Check for mandatory header files
 
-AC_CHECK_HEADERS([arpa/inet.h fcntl.h netdb.h netinet/in.h \ 
+AC_CHECK_HEADERS([arpa/inet.h fcntl.h netdb.h netinet/in.h \
                  sys/ioctl.h sys/socket.h sys/time.h sys/timeb.h wchar.h ]
-                 ,,AC_MSG_ERROR( required header file missing ))
+                 ,,AC_MSG_ERROR([required header file missing]))
 
 ## determine libraries that need to get linked
 
@@ -96,7 +96,7 @@ AC_CHECK_FUNCS([getifaddrs])
 AC_CHECK_FUNCS([alarm ftime gethostbyaddr gethostbyname gettimeofday inet_ntoa \
                memset select socket strchr strdup strerror strncasecmp strstr \
                gethostname]
-               ,,AC_MSG_ERROR( required library function missing ))
+               ,,AC_MSG_ERROR([required library function missing]))
 AC_FUNC_MALLOC
 AC_FUNC_REALLOC
 AC_HEADER_RESOLV
@@ -117,8 +117,8 @@ case $host in
 	      PKG_CHECK_MODULES([LIBUSB1], [libusb-1.0]);;
 
   *-freebsd*) AC_DEFINE_UNQUOTED(HOST_OS,FREEBSD,[Host OS])
-              AC_CHECK_LIB([usb], libusb_init,, AC_MSG_ERROR(Library not found),);;
-  *-*-*) AC_MSG_ERROR( Host OS not (yet) supported) ;;
+              AC_CHECK_LIB([usb], libusb_init,, AC_MSG_ERROR([Library not found]),);;
+  *-*-*) AC_MSG_ERROR([Host OS not (yet) supported]) ;;
 esac
 
 ## Variables to be exported