auth: add test to make sure NSEC(3) generation is case insensitive

auth: add test to make sure NSEC(3) generation is case insensitive

test result before fix (auth-4.0.3):

--- ./tests/nsecx-upcase/expected_result        2017-05-03 21:17:26.000000000 +0200
+++ ./tests/nsecx-upcase/real_result    2017-05-03 21:29:10.231994921 +0200
@@ -2,8 +2,10 @@
 0      Z1234567890.wtest.com.  IN      RRSIG   3600    CNAME 13 2 3600 [expiry] [inception] [keytag] wtest.com. ...
 0      server1.wtest.com.      IN      A       3600    1.2.3.4
 0      server1.wtest.com.      IN      RRSIG   3600    A 13 3 3600 [expiry] [inception] [keytag] wtest.com. ...
-1      a.something.wtest.com.  IN      NSEC    86400   wtest.com. A RRSIG NSEC
-1      a.something.wtest.com.  IN      RRSIG   86400   NSEC 13 4 86400 [expiry] [inception] [keytag] wtest.com. ...
+1      *.wtest.com.    IN      NSEC    86400   e.wtest.com. CNAME RRSIG NSEC
+1      *.wtest.com.    IN      RRSIG   86400   NSEC 13 2 86400 [expiry] [inception] [keytag] wtest.com. ...
 2      .       IN      OPT     32768
 Rcode: 0 (No Error), RD: 0, QR: 1, TC: 0, AA: 1, opcode: 0
 Reply to question for qname='Z1234567890.wtest.com.', qtype=A
./tests/nsecx-upcase/unbound-host.out:Z1234567890.wtest.com is an alias for server1.wtest.com. (BOGUS (security failure))
./tests/nsecx-upcase/unbound-host.out:server1.wtest.com has address 1.2.3.4 (BOGUS (security failure))