Uniquify test case descriptions

Make check-test-cases.py pass.

Prior to this commit, there were many repeated test descriptions, but
none with the same test data and dependencies and comments, as checked
with the following command:

    for x in tests/suites/*.data; do perl -00 -ne 'warn "$ARGV: $. = $seen{$_}\n" if $seen{$_}; $seen{$_}=$.' $x; done

Wherever a test suite contains multiple test cases with the exact same
description, add " [#1]", " [#2]", etc. to make the descriptions
unique. We don't currently use this particular arrangement of
punctuation, so all occurrences of " [#" were added by this script.

I used the following ad hoc code:

import sys

def fix_test_suite(data_file_name):
    in_paragraph = False
    total = {}
    index = {}
    lines = None
    with open(data_file_name) as data_file:
        lines = list(data_file.readlines())
        for line in lines:
            if line == '\n':
                in_paragraph = False
                continue
            if line.startswith('#'):
                continue
            if not in_paragraph:
                # This is a test case description line.
                total[line] = total.get(line, 0) + 1
                index[line] = 0
            in_paragraph = True
    with open(data_file_name, 'w') as data_file:
        for line in lines:
            if line in total and total[line] > 1:
                index[line] += 1
                line = '%s [#%d]\n' % (line[:-1], index[line])
            data_file.write(line)

for data_file_name in sys.argv[1:]:
    fix_test_suite(data_file_name)
diff --git a/tests/suites/test_suite_cipher.null.data b/tests/suites/test_suite_cipher.null.data
index 371b306..3a063ab 100644
--- a/tests/suites/test_suite_cipher.null.data
+++ b/tests/suites/test_suite_cipher.null.data
@@ -78,15 +78,15 @@
 depends_on:MBEDTLS_CIPHER_NULL_CIPHER
 enc_dec_buf_multipart:MBEDTLS_CIPHER_NULL:0:15:1:-1:15:1:15:1
 
-NULL Encrypt and decrypt 22 bytes in multiple parts 1
+NULL Encrypt and decrypt 22 bytes in multiple parts 1 [#1]
 depends_on:MBEDTLS_CIPHER_NULL_CIPHER
 enc_dec_buf_multipart:MBEDTLS_CIPHER_NULL:0:15:7:-1:15:7:15:7
 
-NULL Encrypt and decrypt 22 bytes in multiple parts 1
+NULL Encrypt and decrypt 22 bytes in multiple parts 1 [#2]
 depends_on:MBEDTLS_CIPHER_NULL_CIPHER
 enc_dec_buf_multipart:MBEDTLS_CIPHER_NULL:0:16:6:-1:16:6:16:6
 
-NULL Encrypt and decrypt 22 bytes in multiple parts 1
+NULL Encrypt and decrypt 22 bytes in multiple parts 1 [#3]
 depends_on:MBEDTLS_CIPHER_NULL_CIPHER
 enc_dec_buf_multipart:MBEDTLS_CIPHER_NULL:0:17:6:-1:17:6:17:6