abuild: add support for replaces_priority

abuild.in

@@ -133,6 +133,9 @@ default_sanitycheck() {
 	[ -z "$url" ] && die "Missing url in APKBUILD"
 	[ -z "$license" ] && die "Missing license in APKBULID"
 
+	if [ -n "$replaces_prority" ] && ! egrep -q '^[0-9]+$'; then
+		die "replaces_priority must be a number"
+	fi
 	# check so no package names starts with -
 	for i in $pkgname $subpackages; do
 		case $i in
@@ -712,6 +715,10 @@ EOF
 		echo "maintainer = $maintainer" >> "$pkginfo"
 	fi
 
+	if [ -n "$replaces_priority" ]; then
+		echo "replaces_priority = $replaces_priority"
+	fi
+
 	for i in $license; do
 		echo "license = $i" >> "$pkginfo"
 	done