main/postfix: fix build on aarch64

seems like `install -d` didnt work in fakeroot on aarch64 for some reason

main/postfix/APKBUILD

@@ -29,9 +29,9 @@ _shared_libs() {
 		awk -F: '$2 ~ /sharedlib/ {print $1}'
 }
 
-_builddir="$srcdir"/$pkgname-$pkgver
+builddir="$srcdir"/$pkgname-$pkgver
 prepare() {
-	cd $_builddir
+	cd $builddir
 	for i in $source; do
 		case $i in
 		*.patch) msg $i; patch -p1 -i "$srcdir"/$i || return 1;;
@@ -45,7 +45,7 @@ prepare() {
 }
 
 build() {
-	cd $_builddir
+	cd $builddir
 	# needed for dynamic maps.
 	local ccargs="-DHAS_SHL_LOAD -DDEF_DAEMON_DIR=\\\"/usr/lib/postfix\\\""
 	local auxlibs="$LDFLAGS"
@@ -108,7 +108,8 @@ d
 }
 
 package() {
-	cd $_builddir
+	cd "$builddir"
+
 	make non-interactive-package \
 		install_root="$pkgdir" \
 		readme_directory=/usr/share/doc/$pkgname/readme \
@@ -128,7 +129,7 @@ package() {
 	mv "$pkgdir"/etc/postfix/*LICENSE* \
 		"$pkgdir"/usr/share/licenses/${pkgname}/ || return 1
 
-	install -d -o postfix -g postfix "$pkgdir"/var/spool/postfix
+	chown postfix:postfix "$pkgdir"/var/spool/postfix
 	install -Dm755 "$srcdir"/$pkgname.initd "$pkgdir"/etc/init.d/$pkgname
 	chown postfix "$pkgdir"/var/spool/postfix/* "$pkgdir"/var/lib/postfix \
 		|| return 1
@@ -163,7 +164,7 @@ pgsql() { _mv_dict pgsql ; }
 sqlite() { _mv_dict sqlite ; }
 
 stone() {
-	cd $_builddir
+	cd $builddir
 	pkgdesc="Postfix simulation and testing tools"
 	install -Dm755 src/fsstone/fsstone "$subpkgdir"/usr/bin/fsstone
 	find src/smtpstone -perm 0755 -exec cp {} "$subpkgdir"/usr/bin \;