testing/lttng-ust: use default prepare and builddir

testing/lttng-ust/APKBUILD

@@ -18,20 +18,10 @@ source="https://lttng.org/files/$pkgname/$pkgname-$pkgver.tar.bz2
 	limits-h.patch
 	glibc-strerr-r.patch"
 
-_builddir="$srcdir"/$pkgname-$pkgver
-
-prepare() {
-	local i
-	cd "$_builddir"
-	for i in $source; do
-		case $i in
-		*.patch) msg $i; patch -p1 -i "$srcdir"/$i || return 1;;
-		esac
-	done
-}
+builddir="$srcdir"/$pkgname-$pkgver
 
 build() {
-	cd "$_builddir"
+	cd "$builddir"
 	./configure \
 		--prefix=/usr \
 		|| return 1
@@ -40,7 +30,7 @@ build() {
 }
 
 package() {
-	cd "$_builddir"
+	cd "$builddir"
 	make DESTDIR="$pkgdir" install || return 1
 }