main/zstd: backport compile fixes from 3.14

main/zstd/APKBUILD

@@ -19,6 +19,13 @@ source="zstd-$pkgver.tar.gz::https://github.com/facebook/zstd/archive/v$pkgver.t
 #   1.3.8-r0:
 #     - CVE-2019-11922
 
+unset CPPFLAGS
+export CFLAGS="$CFLAGS -O2 -fno-strict-aliasing -fPIC"
+case "$CARCH" in
+        # avoid memory copy hack that violates C standard
+        armhf) export CFLAGS="$CFLAGS -DMEM_FORCE_MEMORY_ACCESS=0" ;;
+esac
+
 build() {
 	unset CPPFLAGS
 	local _moreflags="-O2 -fno-strict-aliasing"