Add test for valid mode parsing result

While fixing #14, what pointed me to check parsing validity (and not
local issues as I thought at first) was that `-v -v` was showing empty
mode definitions, despite claiming parse success. So let's add a test
that mode parsing does do things, not just empty claims.

Makefile

@@ -67,8 +67,12 @@ distcheck: dist
 	tar xvf $(TARFILE) -C "$$SRC" && \
 	cd "$$SRC/$(RELEASEDIR)" && \
 	make CFLAGS="-Wall -Wextra -Werror" && \
+	echo Checking version output && \
 	./mt --version && ./stinit --version && \
+	echo Checking parse status && \
 	./stinit -p -f stinit.def.examples && \
+	echo Checking complete stinit parsing && \
+	( ./stinit -v -v -p -f stinit.def.examples 2>&1 | grep -q 'Mode 1 definition: scsi2logical=1 can-bsr=1 auto-lock=0 two-fms=0 drive-buffering=1 buffer-writes read-ahead=1 async-writes=1 can-partitions=0 fast-eom=1 blocksize=0 sili=1   timeout=900  long-timeout=14400     density=0x44 compression=0' ) && \
 	make dist && \
 	make install DESTDIR="$$DST" && \
 	numfiles=$$( \