build: 'check-system' now depends on the bootstrap Guile tarballs.

Reported by Chris Marusich <cmmarusich@gmail.com>.

* gnu/local.mk (BOOTSTRAP_GUILE_TARBALLS): New variable.
(DISTCLEANFILES): Define as an alias for 'BOOTSTRAP_GUILE_TARBALLS'.
* Makefile.am (check-system): Depend on $(BOOTSTRAP_GUILE_TARBALLS).

Makefile.am

@@ -379,7 +379,7 @@ check-local:
 
 endif !CAN_RUN_TESTS
 
-check-system: $(GOBJECTS)
+check-system: $(GOBJECTS) $(BOOTSTRAP_GUILE_TARBALLS)
 	$(AM_V_at)$(top_builddir)/pre-inst-env			\
 	   $(GUILE) --no-auto-compile				\
 	   -e '(@@ (run-system-tests) run-system-tests)'	\

gnu/local.mk

@@ -1087,13 +1087,15 @@ nodist_bootstrap_mips64el_linux_DATA =					\
 set-bootstrap-executable-permissions:
 	chmod +x $(DESTDIR)$(bootstrapdir)/*/{bash,mkdir,tar,xz}
 
-DISTCLEANFILES =				\
+BOOTSTRAP_GUILE_TARBALLS =			\
   $(nodist_bootstrap_x86_64_linux_DATA)		\
   $(nodist_bootstrap_i686_linux_DATA)		\
   $(nodist_bootstrap_armhf_linux_DATA)		\
-  $(nodist_bootstrap_aarch64_linux_DATA)		\
+  $(nodist_bootstrap_aarch64_linux_DATA)	\
   $(nodist_bootstrap_mips64el_linux_DATA)
 
+DISTCLEANFILES = $(BOOTSTRAP_GUILE_TARBALLS)
+
 # Method to download a file from an external source.
 DOWNLOAD_FILE =								\
   GUILE_LOAD_COMPILED_PATH="$(top_builddir):$$GUILE_LOAD_COMPILED_PATH"	\