altivec support under netbsd, patch by Matthew Green

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@12142 b3059339-0415-0410-9bf9-f77b7e298cf2

configure

@@ -878,6 +878,18 @@ EOF
 	    _altivec=yes
 	fi
     fi
+    # only gcc 3.4 works reliably with altivec code under netbsd 
+    if netbsd ; then
+	case $cc_version in
+	    2*|3.0*|3.1*|3.2*|3.3*)
+		;;
+	    *)
+		if [ `sysctl -n machdep.altivec` -eq 1 ]; then
+		    _altivec=yes
+		fi
+		;;
+	esac
+    fi
     if test "$_altivec" = yes; then
         echores "$proc altivec"
     else