libXfont2 fail with libbsd

[adr%SDF.ORG@localhost]

Hello.

Systems (well, at least linux) with libbsd installed will
fail to compile libXfont2.
=========================================
src/util/fontxlfd.c: In function 'append_ranges':
src/util/fontxlfd.c:361:9: error: implicit declaration of function 'strlcat'; did you mean 'strncat'? [-Werror=implicit-function-declaration]
  361 |         strlcat(fname, "[", fnamelen);
      |         ^~~~~~~
      |         strncat
src/util/fontxlfd.c:361:9: warning: nested extern declaration of 'strlcat' [-Wnested-externs]
src/util/fontxlfd.c: In function 'FontParseXLFDName':
src/util/fontxlfd.c:453:2: error: implicit declaration of function 'strlcpy'; did you mean 'strncpy'? [-Werror=implicit-function-declaration]
  453 |  strlcpy(tmpBuf, ptr2, sizeof(tmpBuf));
      |  ^~~~~~~
      |  strncpy
src/util/fontxlfd.c:453:2: warning: nested extern declaration of 'strlcpy' [-Wnested-externs]
cc1: some warnings being treated as errors
*** Error code 1
=========================================

You can add something like this to Makefile.

.if exists(/usr/include/bsd/string.h)
CPPFLAGS+=      -DHAVE_LIBBSD
.endif

Although the better would be to add upstream code to set this
variable, it looks like they forgot about it.

Regards,
adr.