Fix help of yosys-config.in and provide backward compatibility

misc/yosys-config.in

@@ -9,16 +9,18 @@ help() {
 		echo "Replacement args:"
 		echo "    --cxx         @CXX@"
 		echo "    --cxxflags    $( echo '@CXXFLAGS@' | fmt -w60 | sed ':a;N;$!ba;s/\n/ \\\n                      /g' )"
-		echo "    --ldflags     @LINKFLAGS@"
-		echo "    --ldlibs      @LIBS@"
+		echo "    --linkflags   @LINKFLAGS@"
+		echo "    --ldflags     (alias of --linkflags)"
+		echo "    --libs        @LIBS@"
+		echo "    --ldlibs      (alias of --libs)"
 		echo "    --bindir      @BINDIR@"
 		echo "    --datdir      @DATDIR@"
 		echo ""
 		echo "All other args are passed through as they are."
 		echo ""
 		echo "Use --exec to call a command instead of generating output. Example usage:"
 		echo ""
-		echo "  $0 --exec --cxx --cxxflags --ldflags -o plugin.so -shared plugin.cc --ldlibs"
+		echo "  $0 --exec --cxx --cxxflags --ldflags -o plugin.so -shared plugin.cc --libs"
 		echo ""
 		echo "The above command can be abbreviated as:"
 		echo ""
@@ -44,7 +46,7 @@ fi
 
 if [ "$1" == "--build" ]; then
 	modname="$2"; shift 2
-	set -- --exec --cxx --cxxflags --ldflags -o "$modname" -shared "$@" --ldlibs
+	set -- --exec --cxx --cxxflags --ldflags -o "$modname" -shared "$@" --libs
 fi
 
 prefix="--"
@@ -63,6 +65,10 @@ for opt; do
 			tokens=( "${tokens[@]}"  @CXX@       ) ;;
 		"$prefix"cxxflags)
 			tokens=( "${tokens[@]}"  @CXXFLAGS@  ) ;;
+		"$prefix"linkflags)
+			tokens=( "${tokens[@]}"  @LINKFLAGS@   ) ;;
+		"$prefix"libs)
+			tokens=( "${tokens[@]}"  @LIBS@    ) ;;
 		"$prefix"ldflags)
 			tokens=( "${tokens[@]}"  @LINKFLAGS@   ) ;;
 		"$prefix"ldlibs)