sys-fs/btrfs-progs: Sync with Gentoo

It's from Gentoo commit a429b970949c21e97dfc4e6b8cee01ed0bb4e2ff.

sdk_container/src/third_party/portage-stable/sys-fs/btrfs-progs/btrfs-progs-6.9.2.ebuild

@@ -35,7 +35,7 @@ HOMEPAGE="https://btrfs.readthedocs.io/en/latest/"
 
 LICENSE="GPL-2"
 SLOT="0/0" # libbtrfs soname
-IUSE="+convert +man reiserfs static static-libs udev +zstd"
+IUSE="+convert +man experimental reiserfs static static-libs udev +zstd"
 # Could support it with just !systemd => eudev, see mdadm, but let's
 # see if someone asks for it first.
 REQUIRED_USE="static? ( !udev )"
@@ -131,7 +131,7 @@ src_configure() {
 		--bindir="${EPREFIX}"/sbin
 
 		--enable-lzo
-		--disable-experimental
+		$(use_enable experimental)
 		--disable-python
 		$(use_enable convert)
 		$(use_enable man documentation)
@@ -171,6 +171,11 @@ src_install() {
 
 	emake V=1 DESTDIR="${D}" install "${makeargs[@]}"
 
+	if use experimental; then
+		exeinto /sbin
+		doexe btrfs-corrupt-block
+	fi
+
 	newbashcomp btrfs-completion btrfs
 }
 

sdk_container/src/third_party/portage-stable/sys-fs/btrfs-progs/metadata.xml

@@ -7,6 +7,7 @@
   </maintainer>
   <use>
     <flag name="convert">Build ext2 conversion utility (btrfs-convert)</flag>
+    <flag name="experimental">Enable unstable and experimental features and install btrfs-corrupt-block, as needed by xfstests</flag>
     <flag name="reiserfs">Enable reiserfs support in btrfs-convert tool.</flag>
     <flag name="static">Build static binaries in addition to the dynamic ones</flag>
   </use>