Minijail: remove libsyscalls.gen.o from test-clean target.

CFLAGS testing change does not affect libsyscalls.gen.o,
and this way we can enable the 'tests' target in the
Minijail ebuild, instead of building the unittest targets
separately.

BUG=None
TEST=cros_workon make chromeos-minijail --test, tests build and run.

Change-Id: If49d74d2db77698d9613b801661f8f75bc29d7be
Reviewed-on: https://gerrit.chromium.org/gerrit/32031
Tested-by: Jorge Lucangeli Obes <jorgelo@chromium.org>
Reviewed-by: Will Drewry <wad@chromium.org>
Commit-Ready: Jorge Lucangeli Obes <jorgelo@chromium.org>
diff --git a/Makefile b/Makefile
index 80eae9e..5983e3a 100644
--- a/Makefile
+++ b/Makefile
@@ -97,12 +97,12 @@
 
 # Only clean up files affected by the CFLAGS change for testing.
 test-clean :
-	@rm -f libminijail.o libminijail_unittest.o libsyscalls.gen.o
+	@rm -f libminijail.o libminijail_unittest.o
 
 clean : test-clean
 	@rm -f libminijail.o libminijailpreload.so minijail0
 	@rm -f libminijail.so
 	@rm -f libminijail_unittest
-	@rm -f libsyscalls.gen.c
+	@rm -f libsyscalls.gen.o libsyscalls.gen.c
 	@rm -f syscall_filter.o signal.o bpf.o util.o
 	@rm -f syscall_filter_unittest syscall_filter_unittest.o