OpenBSD's file(1) doesn't support the --mime-encoding option, so remove
those checks as they cause the build to fail.

Index: src/Makefile.in
--- src/Makefile.in.orig
+++ src/Makefile.in
@@ -2290,15 +2290,7 @@ uninstall-am: uninstall-binPROGRAMS
 
 infocontrib.h: $(srcdir)/buildtools/geninfocontrib_h.sh $(top_srcdir)/doc/vice.texi $(srcdir)/buildtools/infocontrib.sed
 	@echo "generating infocontrib.h"
-	@if [ "`file --mime-encoding $(srcdir)/buildtools/geninfocontrib_h.sh`" != "$(srcdir)/buildtools/geninfocontrib_h.sh: iso-8859-1" ]; then \
-		echo "ERROR: geninfocontrib_h.sh contains content that is not valid iso-8859-x" >&2; \
-		false; \
-	fi
 	@$(SHELL) $(srcdir)/buildtools/geninfocontrib_h.sh infocontrib.h <$(top_srcdir)/doc/vice.texi `grep "VICEDATE_YEAR " $(top_srcdir)/src/vicedate.h | cut -d " " -f 3` | LC_ALL=C sed -f $(srcdir)/buildtools/infocontrib.sed >infocontrib.h
-	@if [ "`file --mime-encoding infocontrib.h`" != "infocontrib.h: iso-8859-1" ]; then \
-		echo "ERROR: generated infocontrib.h contains content that is not valid iso-8859-x" >&2; \
-		false; \
-	fi
 
 # we need to replace \ and space by "regular" characters, else things break on some shells
 	@LC_ALL=C sed -e 's/\\/{/g' -e 's/ /}/g' <$(top_srcdir)/README >./README.tmp