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

*** 14,30 ****
--- 14,36 ----
  # 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)