When querying an info value, copy out exactly as many characters as
the caller asked for -- do not artificially truncate the target just
to ensure that it is \0-terminated.
Specifically: do not use opal_string_copy() to copy info values,
because opal_string_copy() will guarantee to \0-terminate the target,
even if it means truncating the target. E.g., if the caller calls
opal_info_get_nolock() with valuelen=5, opal_string_copy() will return
"1234\0" -- which is wrong. This commit fixes the behavior to return
"12345".
Signed-off-by: Jeff Squyres <jsquyres@cisco.com>