This adds RTL_LOG_STRING_INTERN_NEW and RTL_LOG_STRING_INTERN_DELETE
which are connected to SDT probes if available. It introduces two new
SDT probes. new_string_intern_16 and delete_string_intern_16
(there is currently no interning for 8-bit rtl_Strings).
For consistency both have the same 4 arguments as new_string_(8|16)
and delete_string_(8|16). new_string_intern_16 has as 5th argument
the address of the original rtl_uString being interned (which may
or may not be the same as $arg1).

Change-Id: Ib117bba932c1908abc70a7fdd4140c0af76d54cb
Reviewed-on: https://gerrit.libreoffice.org/5308Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>