Extend the notes on how to do testing

These notes include the use of HARNESS_VERBOSE (see the manual for
Test::Harness) and the method to enumerate specific tests to run.

Reviewed-by: Emilia Käsper <emilia@openssl.org>

INSTALL

@@ -173,14 +173,38 @@
 
        $ make test
 
-     If a test fails, look at the output.  There may be reasons for
-     the failure that isn't a problem in OpenSSL itself (like a missing
-     or malfunctioning bc).  If it is a problem with OpenSSL itself,
-     try removing any compiler optimization flags from the CFLAG line
-     in Makefile.ssl and run "make clean; make". Please send a bug
-     report to <openssl-bugs@openssl.org>, including the output of
-     "make report" in order to be added to the request tracker at
-     http://www.openssl.org/support/rt.html.
+     If some tests fail, look at the output.  There may be reasons for
+     the failure that isn't a problem in OpenSSL itself (like a
+     malfunction with Perl).  You may want increased verbosity, that
+     can be accomplished like this:
+
+       $ HARNESS_VERBOSE=yes make test
+
+     Also, you will find logs for all commands the tests have executed
+     in logs, test/test_*.log, one for each individual test.
+
+     If you want to run just one or a few specific tests, you can use
+     the make variable TESTS to specify them, like this:
+
+       $ make TESTS='test_rsa test_dsa' test
+
+     And of course, you can combine:
+       
+       $ HARNESS_VERBOSE=yes make TESTS='test_rsa test_dsa' test
+
+     You can find the list of available tests like this:
+
+       $ make list-tests
+
+     If you find a problem with OpenSSL itself, try removing any
+     compiler optimization flags from the CFLAG line in Makefile and
+     run "make clean; make".
+
+     Please send a bug report to <openssl-bugs@openssl.org>, and when
+     you do, please run the following and include the output in your
+     report:
+
+       $ make report
 
   4. If everything tests ok, install OpenSSL with