prefix ETCDIR with ${PREFIX}/

`ETCDIR` isn't prefixed and led to dangling files in `DESTDIR/etc`

Signed-off-by: Tobias Wendorff <[email protected]>

Makefile

@@ -39,7 +39,7 @@ BINDIR ?= ${PREFIX}/bin
 LIBEXECDIR ?= ${PREFIX}/libexec
 MANDIR ?= ${PREFIX}/share/man
 SHAREDIR_CONTAINERS ?= ${PREFIX}/share/containers
-ETCDIR ?= /etc
+ETCDIR ?= ${PREFIX}/etc
 TMPFILESDIR ?= ${PREFIX}/lib/tmpfiles.d
 SYSTEMDDIR ?= ${PREFIX}/lib/systemd/system
 USERSYSTEMDDIR ?= ${PREFIX}/lib/systemd/user