gcc: Don't run the test suite when Guile is unavailable.

* configure.ac: Remove `HAVE_GUILE' Automake conditional; add
  `RUN_GCC_PLUGIN_TESTS' Automake conditional based on
  $run_gcc_plugin_test_suite.

* gcc-plugin/tests/Makefile.am (TESTS, TESTS_ENVIRONMENT): Make
  conditional on `RUN_GCC_PLUGIN_TESTS' only.

configure.ac

@@ -1262,7 +1262,8 @@ fi
 AM_MISSING_PROG([YACC], [bison])
 
 AM_CONDITIONAL([BUILD_GCC_PLUGIN], [test "x$build_gcc_plugin" = "xyes"])
-AM_CONDITIONAL([HAVE_GUILE], [test "x$GUILE" != "x"])
+AM_CONDITIONAL([RUN_GCC_PLUGIN_TESTS],
+  [test "x$run_gcc_plugin_test_suite" = "xyes"])
 
 ###############################################################################
 #                                                                             #

gcc-plugin/tests/Makefile.am

@@ -85,20 +85,17 @@ EXTRA_DIST += ./run-test.in			\
   $(gcc_tests)
 
 # The test suite assumes that the CPU back-end is available.
-if STARPU_USE_CPU
+if RUN_GCC_PLUGIN_TESTS
 
 TESTS = $(gcc_tests)
-
-endif
-
 TESTS_ENVIRONMENT = ./run-test
 
-if !HAVE_GUILE
+else !RUN_GCC_PLUGIN_TESTS
 
 check-hook:
-	-@echo "GNU Guile not available, test suite not run."
+	-@echo "GNU Guile or CPU back-end not available, test suite not run."
 
-endif !HAVE_GUILE
+endif !RUN_GCC_PLUGIN_TESTS
 
 showcheck:
 	-cat $(TEST_LOGS) /dev/null