configure.in: no -Wextra-token on gcc 3

* configure.in (warnflags): -Wextra-tokens is same as -Wextra and
  let -Wno- options ignored on gcc 3.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40131 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -419,6 +419,8 @@ AC_SUBST(LD)
 if test "$GCC" = yes; then
     linker_flag=-Wl,
     : ${optflags=-O3}
+    gcc_major=`echo =__GNUC__ | $CC -E -xc - | sed '/^=/!d;s///'`
+    test -n "$gcc_major" || gcc_major=0
     # RUBY_APPEND_OPTIONS(XCFLAGS, ["-include ruby/config.h" "-include ruby/missing.h"])
 else
     linker_flag=
@@ -664,6 +666,11 @@ AC_ARG_ENABLE(werror,
 
 rb_cv_warnflags="$warnflags"
 if test "$GCC:${warnflags+set}:no" = yes::no; then
+    if test $gcc_major -ge 4; then
+	extra_warning=-Werror=extra-tokens
+    else
+	extra_warning=
+    fi
     for wflag in -Wno-unused-parameter -Wno-parentheses -Wno-long-long \
 		 -Wno-missing-field-initializers \
 		 -Wunused-variable \
@@ -672,7 +679,7 @@ if test "$GCC:${warnflags+set}:no" = yes::no; then
 		 -Werror=declaration-after-statement \
 		 -Werror=shorten-64-to-32 \
 		 -Werror=implicit-function-declaration \
-		 -Werror=extra-tokens \
+		 $extra_warning \
 		 ; do
 	if test "$particular_werror_flags" != yes; then
 	    wflag=`echo x$wflag | sed 's/^x-Werror=/-W/;s/^x//'`