testsuite: add timeout for each test

Each test must run under 2 seconds. Ideally they should run in much less
than this; just give an arbitrary number so we don't wait forever in
case we reached an infinite loop somewhere.
diff --git a/Makefile.am b/Makefile.am
index 5751dbd..faad5b8 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -169,6 +169,7 @@
 testsuite_libtestsuite_la_DEPENDENCIES = $(ROOTFS) \
 					 $(TESTSUITE_OVERRIDE_LIBS)
 testsuite_libtestsuite_la_CPPFLAGS = $(TESTSUITE_CPPFLAGS)
+testsuite_libtestsuite_la_LIBADD = -lrt
 
 TESTSUITE = testsuite/test-init testsuite/test-testsuite testsuite/test-loaded \
 	    testsuite/test-modinfo testsuite/test-alias testsuite/test-new-module \