Set automake variable before loading macros so it can be appended

Makefile.am

@@ -24,6 +24,8 @@ EXTRA_DIST += t/000-tear-env.t t/001-setup-env.t t/100-init.t t/300-add.t t/950-
 BUILT_SOURCES =
 CLEANFILES = $(dist_man_MANS) $(bin_SCRIPTS)
 
+DISTCLEANFILES = @AMINCLUDE@
+
 # A classical use of the autoconf-archive include macro would expand
 # INC_AMINCLUDE here, but the perl script that inlines include statements
 # runs before the automake that organizes logic and performs substitution.
@@ -33,8 +35,6 @@ CLEANFILES = $(dist_man_MANS) $(bin_SCRIPTS)
 # functionality and hence can use conditionals in included makefile fragments.
 include $(top_srcdir)/aminclude.am
 
-DISTCLEANFILES = @AMINCLUDE@
-
 if !SOURCE_IS_DIST
 
 doc/vcsh.1: doc/vcsh.1.ronn