The distribution should not contain generated vcc_if files

On getting dependencies right:

See automake doc 9.4.1 Built Sources Example / Recording Dependencies manually

src/Makefile.am

@@ -6,10 +6,14 @@ vmod_LTLIBRARIES = libvmod_example.la
 libvmod_example_la_LDFLAGS = -module -export-dynamic -avoid-version -shared
 
 libvmod_example_la_SOURCES = \
-	vcc_if.c \
-	vcc_if.h \
 	vmod_example.c
 
+nodist_libvmod_example_la_SOURCES = \
+	vcc_if.c \
+	vcc_if.h
+
+vmod_example.lo: vcc_if.c vcc_if.h
+
 vcc_if.c: vcc_if.h
 
 vcc_if.h: @VMODTOOL@ $(top_srcdir)/src/vmod_example.vcc