basic,shared: move a bunch of files to src/shared/

The goal is to move everything that requires selinux or smack
away from src/basic/. This means that src/basic/label.[ch] must move,
which implies btrfs-util.[ch], copy.[ch], and a bunch of other files
which form a cluster of internal use.

This is just moving text around, so there should be no functional difference.

test-blockdev-util is new, because path_is_encrypted() is moved to
blockdev-util.c, and so far we didn't have any tests for code there.

src/basic/meson.build

@@ -15,10 +15,6 @@ basic_sources = files('''
         async.h
         audit-util.c
         audit-util.h
-        blockdev-util.c
-        blockdev-util.h
-        btrfs-util.c
-        btrfs-util.h
         build.c
         build.h
         bus-label.c
@@ -33,12 +29,8 @@ basic_sources = files('''
         chattr-util.h
         conf-files.c
         conf-files.h
-        copy.c
-        copy.h
         creds-util.c
         creds-util.h
-        data-fd-util.c
-        data-fd-util.h
         def.h
         dirent-util.c
         dirent-util.h
@@ -85,8 +77,6 @@ basic_sources = files('''
         ioprio.h
         khash.c
         khash.h
-        label.c
-        label.h
         limits-util.c
         limits-util.h
         linux/btrfs.h
@@ -157,7 +147,6 @@ basic_sources = files('''
         missing_syscall.h
         missing_timerfd.h
         missing_type.h
-        mkdir-label.c
         mkdir.c
         mkdir.h
         mountpoint-util.c
@@ -200,10 +189,6 @@ basic_sources = files('''
         replace-var.h
         rlimit-util.c
         rlimit-util.h
-        rm-rf.c
-        rm-rf.h
-        selinux-util.c
-        selinux-util.h
         set.h
         sigbus.c
         sigbus.h
@@ -211,9 +196,6 @@ basic_sources = files('''
         signal-util.h
         siphash24.c
         siphash24.h
-        smack-util.c
-        smack-util.h
-        socket-label.c
         socket-util.c
         socket-util.h
         sort-util.c