autotest: Fix problem with logging_UserCrash tgz file being masked.

client/site_tests/logging_UserCrash/src/Makefile

Index: client/site_tests/logging_UserCrash/src/Makefile
diff --git a/client/site_tests/logging_UserCrash/src/Makefile b/client/site_tests/logging_UserCrash/src/Makefile
index 838f34c1abde1cc6874dfd046f56c56bff49ee5a..d7dd0000ced2662869eff34f0498ab66876a0325 100644
--- a/client/site_tests/logging_UserCrash/src/Makefile
+++ b/client/site_tests/logging_UserCrash/src/Makefile
@@ -5,13 +5,16 @@
 BINS = crasher_nobreakpad
 SRC = crasher.cc
 OBJS = crasher.o bomb.o
-TGZ = crasher.tgz
+# Use a non-standard extension to avoid the AUTOTEST_MASK that intends to
+# remove these since they're usually large and redundant.
+TGZ = crasher.tgz-unmasked
 
 all: $(TGZ)
 
 # gzip so that portage does not strip.
 $(TGZ): $(BINS)
 	tar czf $(TGZ) $^
+	rm -f $(BINS)
 
 crasher_nobreakpad: $(OBJS)
 	$(CXX) $(CXXFLAGS) -o $@ $^