...the deprecation-warning noise is getting ever louder, and eventually auto_ptr
will just disappear.  Just surrender and use good-old plain pointer and deletion
in dtor---it's probably the best to do in this stable interface.

The change is backwards compatible.  For one, in all relevant standard libraries
(libstdc++, even in debug mode; libc++; msvcrt) sizeof(auto_ptr<T>) equals
sizeof(T*).  And for another, the removed UnoUrlDescriptor ctor was only called
from within cppuhelper and had deliberately been left out of
cppuhelper/source/gcc3.map (so isn't exported at least on Linux)---marking it
SAL_DLLPRIVATE had probably just been forgotten when retrofitting cppuhelper
with CPPUHELPER_DLLPUBLIC annotations.

Change-Id: Ic8bce29d93938f2b2e0a264baee85132668e1294