system/isl: bump to 0.20, modernise

system/isl/APKBUILD

 # Contributor: Timo Teräs <timo.teras@iki.fi>
 # Maintainer: Adelie Platform Group <adelie-devel@lists.adelielinux.org>
 pkgname=isl
-pkgver=0.18
+pkgver=0.20
 pkgrel=0
 pkgdesc="An Integer Set Library for the Polyhedral Model"
 url="http://isl.gforge.inria.fr/"
@@ -12,14 +12,10 @@ depends_dev="gmp-dev"
 makedepends_host="$depends_dev"
 makedepends="$makedepends_host"
 replaces="cloog"
-install=""
 subpackages="$pkgname-dev"
 source="http://isl.gforge.inria.fr/isl-$pkgver.tar.bz2"
 
-builddir="$srcdir"/$pkgname-$pkgver
-
 build() {
-	cd "$builddir"
 	./configure \
 		--build=$CBUILD \
 		--host=$CHOST \
@@ -32,12 +28,10 @@ build() {
 }
 
 check() {
-	cd "$builddir"
 	make check
 }
 
 package() {
-	cd "$builddir"
 	make DESTDIR="$pkgdir" INSTALL="install -D" install
 }
 
@@ -49,4 +43,4 @@ dev() {
 		"$subpkgdir"/usr/share/gdb/python/auto-load/usr/lib/
 }
 
-sha512sums="85d0b40f4dbf14cb99d17aa07048cdcab2dc3eb527d2fbb1e84c41b2de5f351025370e57448b63b2b8a8cf8a0843a089c3263f9baee1542d5c2e1cb37ed39d94  isl-0.18.tar.bz2"
+sha512sums="afe2e159b74646a26449268637403d271f9e3f6410d8cc1c9cffca41370c4357b165dea844db0c2a654591f954e54710dda650c8088abd4711406aa6302da950  isl-0.20.tar.bz2"