Found the following significant warnings:
  libunrtf/attr.h:85:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.h:86:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.h:87:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.h:92:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.h:94:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.h:96:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.h:98:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:71:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:72:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:449:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:512:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:537:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:563:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:603:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:632:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/attr.c:663:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:165:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:222:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:223:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:237:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:257:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:379:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:391:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:3093:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:3114:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:3140:13: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:3164:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/convert.c:3245:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/error.c:67:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/hash.c:84:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/path.h:15:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/path.h:16:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/malloc.c:156:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/parse.c:216:1: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/path.c:70:5: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
  libunrtf/path.c:103:6: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
See ‘/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/unrtf.Rcheck/00install.out’ for details.