checkpolicy: handle unprintable token #560

Job	Run time
build (gcc, 3.11, 3.1)	1m 26s
build (gcc, 3.11, 3.1, test-flags-override)	1m 25s
build (gcc, 3.11, 3.1, test-debug)	1m 50s
build (gcc, 3.11, 3.1, linker-bfd)	2m 54s
build (gcc, 3.11, 3.1, linker-gold)	1m 37s
build (gcc, 3.10, 3.1)	1m 37s
build (gcc, 3.9, 3.1)	1m 37s
build (gcc, 3.8, 3.1)	1m 37s
build (gcc, 3.7, 3.1)	1m 39s
build (gcc, pypy3.7, 3.1)	1m 57s
build (gcc, 3.11, 3.0)	1m 26s
build (gcc, 3.11, 2.7)	2m 27s
build (gcc, 3.11, 2.6)	1m 42s
build (gcc, 3.11, 2.5)	1m 41s
build (clang, 3.11, 3.1)	1m 43s
build (clang, 3.11, 3.1, test-flags-override)	1m 30s
build (clang, 3.11, 3.1, test-debug)	1m 37s
build (clang, 3.10, 3.1)	1m 38s
build (clang, 3.9, 3.1)	1m 39s
build (clang, 3.8, 3.1)	1m 41s
build (clang, 3.7, 3.1)	2m 27s
build (clang, pypy3.7, 3.1)	2m 1s
build (clang, 3.11, 3.0)	1m 39s
build (clang, 3.11, 2.7)	2m 1s
build (clang, 3.11, 2.6)	1m 54s
build (clang, 3.11, 2.5)	1m 52s
build (gcc, 3.11, 3.1, sanitizers)	2m 32s
	49m 9s

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