Remove old tor-fw-helper README from EXTRA_DIST

We removed this file, but didn't take it out of EXTRA_DIST -- thus
breaking "make dist".

src/tools/include.am

@@ -44,8 +44,6 @@ src_tools_tor_cov_gencert_LDADD = src/common/libor-testing.a \
     @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@
 endif
 
-EXTRA_DIST += src/tools/tor-fw-helper/README
-
 if BUILD_LIBTORRUNNER
 noinst_LIBRARIES += src/tools/libtorrunner.a
 src_tools_libtorrunner_a_SOURCES = src/tools/tor_runner.c src/or/tor_api.c