# nifty trick -- make a hash to ease the lookup in the findit sub

my %excludeit;
# now set the keys of the hash 
# (== the members of your excluded directories array) 
# to have values of 1

@excludeit {@exclude_dirs} = (1) x @exclude_dirs;

# this would be the subroutine used by File::Find

sub findit {
	$File::Find::prune = 1 if $excludeit{$_};
	# ..
}