Add lavfi-showfiltfmts and graph2dot to $(TOOLS)

Allow make clean to remove the corresponding binaries.

Fix issue 2162.
Signed-off-by: NMans Rullgard <mans@mansr.com>
(cherry picked from commit cd6a5a57)

Makefile

@@ -15,7 +15,7 @@ OBJS        = $(PROGS-yes:%=%.o) cmdutils.o
 MANPAGES    = $(PROGS-yes:%=doc/%.1)
 PODPAGES    = $(PROGS-yes:%=doc/%.pod)
 HTMLPAGES   = $(PROGS-yes:%=doc/%.html)
-TOOLS       = $(addprefix tools/, $(addsuffix $(EXESUF), cws2fws pktdumper probetest qt-faststart trasher))
+TOOLS       = $(addprefix tools/, $(addsuffix $(EXESUF), cws2fws graph2dot lavfi-showfiltfmts pktdumper probetest qt-faststart trasher))
 TESTTOOLS   = audiogen videogen rotozoom tiny_psnr base64
 HOSTPROGS  := $(TESTTOOLS:%=tests/%)