-Wno-format-nonliteral does not exist in my gcc 2.96, only use that with

newer versions

configure.ac

@@ -1203,7 +1203,7 @@ AC_HELP_STRING([--disable-debug],[Disable debug options]),
          dnl we only like gcc less than 5.0, since if it is above that it is
          dnl likely just a compiler that looks like gcc (like icc 8.0)!
          dnl here's the standard setup
-         WARN="-W -Wall -Wwrite-strings -pedantic -Wno-long-long -Wno-format-nonliteral -Wundef -Wpointer-arith -Wnested-externs -Winline -Wmissing-declarations -Wmissing-prototypes -Wsign-compare"
+         WARN="-W -Wall -Wwrite-strings -pedantic -Wno-long-long -Wundef -Wpointer-arith -Wnested-externs -Winline -Wmissing-declarations -Wmissing-prototypes -Wsign-compare"
 
          dnl -Wcast-align is a bit too annoying ;-)
 
@@ -1211,6 +1211,11 @@ AC_HELP_STRING([--disable-debug],[Disable debug options]),
            dnl gcc 2.96 or later
            WARN="$WARN -Wfloat-equal"
 
+           if test "$gccnum" -gt "296"; then
+             dnl this option does not exist in 2.96
+             WARN="$WARN -Wno-format-nonliteral"
+           fi
+
            dnl -Wunreachable-code seems totally unreliable on my gcc 3.3.2 on
            dnl on i686-Linux as it gives us heaps with false positives
            if test "$gccnum" -ge "303"; then