main/zstd: add cmake files

main/zstd/APKBUILD

@@ -4,12 +4,12 @@
 # Maintainer: psykose <alice@ayaya.dev>
 pkgname=zstd
 pkgver=1.5.2
-pkgrel=5
+pkgrel=6
 pkgdesc="Zstandard - Fast real-time compression algorithm"
 url="https://www.zstd.net/"
 arch="all"
 license="BSD-3-Clause GPL-2.0-or-later"
-makedepends="grep"
+makedepends="cmake grep"
 checkdepends="file"
 subpackages="
 	$pkgname-static
@@ -27,11 +27,16 @@ source="zstd-$pkgver.tar.gz::https://github.com/facebook/zstd/archive/v$pkgver.t
 #   1.3.8-r0:
 #     - CVE-2019-11922
 
-export CFLAGS="${CFLAGS/-Os/-O2} -flto -ffat-lto-objects"
-export CXXFLAGS="${CXXFLAGS/-Os/-O2} -flto -ffat-lto-objects"
-export LDFLAGS="$LDFLAGS -flto"
-
 build() {
+	export CFLAGS="${CFLAGS/-Os/-O2} -flto -ffat-lto-objects"
+	export CXXFLAGS="${CXXFLAGS/-Os/-O2} -flto -ffat-lto-objects"
+	export LDFLAGS="$LDFLAGS -flto"
+
+	# just used to generate the .cmake files
+	cmake -B build-zstd \
+		-DCMAKE_INSTALL_PREFIX=/usr \
+		-DCMAKE_BUILD_TYPE=Release \
+		-S build/cmake
 	make -C lib prefix=/usr HAVE_PTHREAD=1
 	make -C programs prefix=/usr HAVE_PTHREAD=1
 	make -C contrib/pzstd prefix=/usr HAVE_PTHREAD=1
@@ -45,6 +50,10 @@ check() {
 package() {
 	make prefix=/usr DESTDIR="$pkgdir" HAVE_PTHREAD=1 install
 	install -Dm755 contrib/pzstd/pzstd -t "$pkgdir"/usr/bin/
+
+	install -Dm644 -t "$pkgdir"/usr/lib/cmake/zstd/ \
+		build-zstd/CMakeFiles/Export/*/*.cmake \
+		build-zstd/zstdConfig*.cmake
 }
 
 sha512sums="