Strip the target triplet GNU suffix more precisely.

Make the regular expressions more precise (anchor them to
the end of the input string), and try to catch any future
unrecognized target triplets by checking for a "-gnu" part
left over after the known variants were supposedly stripped.

configure.ac

@@ -857,24 +857,27 @@ AC_DEFINE_UNQUOTED([GID_0_GROUP],["$group_with_gid0"],[Get the group name having
 # get rid of the 4-th tuple, if config.guess returned "linux-gnu" for host_os
 #
 host_os_gnu=-gnu
-if echo "$host_os" | grep '.*-gnulibc1' > /dev/null ; then
+if echo "$host_os" | grep '.*-gnulibc1$' > /dev/null ; then
 	host_os=`echo "${host_os}" | sed 's/-gnulibc1$//'`
 fi
-if echo "$host_os" | grep '.*-gnueabihf' > /dev/null ; then
+if echo "$host_os" | grep '.*-gnueabihf$' > /dev/null ; then
 	host_os=`echo "${host_os}" | sed 's/-gnueabihf$//'`
 	host_os_gnu=-gnueabihf
 fi
-if echo "$host_os" | grep '.*-gnueabi' > /dev/null ; then
+if echo "$host_os" | grep '.*-gnueabi$' > /dev/null ; then
 	host_os=`echo "${host_os}" | sed 's/-gnueabi$//'`
 	host_os_gnu=-gnueabi
 fi
-if echo "$host_os" | grep '.*-gnuabi64' > /dev/null ; then
+if echo "$host_os" | grep '.*-gnuabi64$' > /dev/null ; then
 	host_os=`echo "${host_os}" | sed 's/-gnuabi64$//'`
 	host_os_gnu=-gnuabi64
 fi
-if echo "$host_os" | grep '.*-gnu' > /dev/null ; then
+if echo "$host_os" | grep '.*-gnu$' > /dev/null ; then
 	host_os=`echo "${host_os}" | sed 's/-gnu$//'`
 fi
+if echo "$host_os" | grep '.*-gnu[[^-]]*$' > /dev/null ; then
+	AC_MSG_ERROR([unrecognized GNU build triplet $host_os])
+fi
 
 changequote(<, >)
 host_os_exact="${host_os}"