abuild: add sanitycheck of provides

provides cannot contain the pkgname or apk will be very unhappy.

abuild.in

@@ -238,6 +238,8 @@ default_sanitycheck() {
 			die "Testsuites (abuild check) are required or needs to be explicitly disabled!"
 	fi
 
+	check_provides || die "provides must not contain $pkgname"
+
 	return 0
 }
 
@@ -859,6 +861,16 @@ check_depends_dev() {
 	return 1
 }
 
+check_provides() {
+	local i
+	for i in $provides; do
+		if [ "${i%%[<>=]*}" = "$pkgname" ]; then
+			return 1
+		fi
+	done
+	return 0
+}
+
 prepare_metafiles() {
 	getpkgver || return 1
 	local name=${subpkgname:-$pkgname}