Tweaks per Hans.
Add check target by default.  Fix packaging.  And make check output match
hdrchk, etc.

@@ -14,17 +14,23 @@
 # Copyright 2014 Garrett D'Amore <garrett@damore.org>
 #
 
 PROGS=          mandoc mandoc_preconv
 
+# We place preconv in /usr/lib.  This is done to avoid conflicting with
+# GNU groff, which puts it into /usr/bin.  We also rename it so that it
+# will only be seen by mandoc -- it isn't intended for general end-user use.
+
 ROOTPROGS =     $(ROOTBIN)/mandoc $(ROOTLIB)/mandoc_preconv
 
 OBJS=           $(preconv_OBJS) $(mandoc_OBJS)
 
 include         $(SRC)/cmd/Makefile.cmd
 include         $(SRC)/cmd/mandoc/Makefile.common
 
+.KEEP_STATE:
+
 all:            $(PROGS)
 
 mandoc_preconv: $(preconv_OBJS)
                 $(LINK.c) $(preconv_OBJS) -o $@ $(LDLIBS)
                 $(POST_PROCESS)