Really clean files not meant for make dist, dist-hook is invoked

only in toplevel project!

Makefile.am

@@ -39,3 +39,6 @@ lcov:
 	($(MAKE); cd unit_tests; $(MAKE) lcov)
 quick-check:
 	($(MAKE); cd unit_tests; $(MAKE) quick-check)
+
+dist-hook:
+	make -C libclamav/c++ dist-hook

Makefile.in

@@ -741,6 +741,9 @@ distdir: $(DISTFILES)
 	      || exit 1; \
 	  fi; \
 	done
+	$(MAKE) $(AM_MAKEFLAGS) \
+	  top_distdir="$(top_distdir)" distdir="$(distdir)" \
+	  dist-hook
 	-test -n "$(am__skip_mode_fix)" \
 	|| find "$(distdir)" -type d ! -perm -777 -exec chmod a+rwx {} \; -o \
 	  ! -type d ! -perm -444 -links 1 -exec chmod a+r {} \; -o \
@@ -965,8 +968,8 @@ uninstall-am: uninstall-binSCRIPTS uninstall-pkgconfigDATA
 .PHONY: $(RECURSIVE_CLEAN_TARGETS) $(RECURSIVE_TARGETS) CTAGS GTAGS \
 	all all-am am--refresh check check-am clean clean-generic \
 	clean-libtool ctags ctags-recursive dist dist-all dist-bzip2 \
-	dist-gzip dist-lzma dist-shar dist-tarZ dist-xz dist-zip \
-	distcheck distclean distclean-generic distclean-hdr \
+	dist-gzip dist-hook dist-lzma dist-shar dist-tarZ dist-xz \
+	dist-zip distcheck distclean distclean-generic distclean-hdr \
 	distclean-libtool distclean-tags distcleancheck distdir \
 	distuninstallcheck dvi dvi-am html html-am info info-am \
 	install install-am install-binSCRIPTS install-data \
@@ -986,6 +989,9 @@ lcov:
 quick-check:
 	($(MAKE); cd unit_tests; $(MAKE) quick-check)
 
+dist-hook:
+	make -C libclamav/c++ dist-hook
+
 # Tell versions [3.59,3.63) of GNU make to not export all variables.
 # Otherwise a system limit (for SysV at least) may be exceeded.
 .NOEXPORT: