mxraid_assemble: specify database file as option

This allows checkin the db-file before it gets disted.

mxraid/mxraid_assemble

@@ -30,6 +30,7 @@ sub exec_usage {
 
       -a        assemble arrays when run as root
       -c        check database
+      -d file   alternative database file
       -h        print this help and exit
       -q        be quiet
       -v        be more verbose
@@ -62,7 +63,7 @@ sub exec_version {
 my $ROOT=$<==0?1:0;
 
 my %opts;
-getopts('achqvV', \%opts) or die "# ERROR: getopts failed, try -h.\n";  # Values in %opts
+getopts('acd:hqvV', \%opts) or die "# ERROR: getopts failed, try -h.\n";  # Values in %opts
 exec_usage if $opts{h};
 exec_version if $opts{V};
 
@@ -73,6 +74,15 @@ $VERBOSE+=1 if $opts{v};
 
 
 my $MDADMCONF_DB =    '/etc/mxmd.conf';      # the 'database' with serials
+if ($opts{d}) {
+  my $db = $opts{d};
+  if (-e $db) {
+    $MDADMCONF_DB = $db;
+  } else {
+    die "# db file '$db' does not exist, stopped";
+  }
+}
+
 my $MDADM_CONF_BASE = '/dev/shm/mdadm.conf'; # config for mdadm, created with information from above
 
 my $MDADM_ASSEMBLE_OPTIONS = '';