gherkin: Use awk to remove BOM (sed trick doesn't work on OSX)

Author: aslakhellesoy

Makefile

@@ -67,7 +67,7 @@ libs_so: ./include/rule_type.h src/parser.c src/dialect.c $(SRC_FILES) src/Makef
 	# have mono, so we'll allow this line to fail.
 	-mono berp/berp.exe -g gherkin.berp -t gherkin-c-rule-type.razor -o $@
 	# Remove BOM
-	sed '1s/^\xEF\xBB\xBF//' < $@ > $@.nobom
+	awk 'NR==1{sub(/^\xef\xbb\xbf/,"")}{print}' < $@ > $@.nobom
 	mv $@.nobom $@
 
 src/parser.c: gherkin.berp gherkin-c-parser.razor
@@ -77,7 +77,7 @@ src/parser.c: gherkin.berp gherkin-c-parser.razor
 	# have mono, so we'll allow this line to fail.
 	-mono berp/berp.exe -g gherkin.berp -t gherkin-c-parser.razor -o $@
 	# Remove BOM
-	sed '1s/^\xEF\xBB\xBF//' < $@ > $@.nobom
+	awk 'NR==1{sub(/^\xef\xbb\xbf/,"")}{print}' < $@ > $@.nobom
 	mv $@.nobom $@
 
 src/dialect.c: gherkin-languages.json dialect.c.jq