remove unnecessary 'using namespace rtl' declarations

It turns out that almost none of them were necessary.

Change-Id: I1311ed28409c682b57ea8d149bcbaf2c49133e83
Reviewed-on: https://gerrit.libreoffice.org/12133
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>

bridges/source/cpp_uno/gcc3_linux_powerpc64/uno2cpp.cxx

@@ -34,7 +34,6 @@
 #include <string.h>
 
 
-using namespace ::rtl;
 using namespace ::com::sun::star::uno;
 
 namespace ppc64