libpq++ current sources don't compile with older C++ compilers

Today I did something I usually do about once per release cycle: try to
build the system with HP's vendor cc, rather than gcc which I prefer.
This usually turns up some portability issues, and indeed I found some.
One that I'm not entirely sure about how to fix is that libpq++ no 
longer builds at all:

aCC  +z -I../../../src/interfaces/libpq -I../../../src/include -I/usr/local/include  -c -o pgconnection.o
pgconnection.cc
Error 56: "pgconnection.cc", line 20 # Namespaces are not yet implemented.   using namespace std;
^^^^^^^^^^^^^^^^^^^^

Given that we have a HAVE_NAMESPACE_STD configure symbol, I do not
understand why unconditional "using"s have been inserted into the
libpq++ files.  Shouldn't these be protected by #ifdef
HAVE_NAMESPACE_STD?  Or is there a different fix that's more
appropriate?
        regards, tom lane