r2263: When testing whether building shared libraries actually works, use

r2263: When testing whether building shared libraries actually works, use
$SHLD and $LDSHFLAGS instead of $CC, $CPPFLAGS and $CFLAGS as this is
more likely to actually work.  Bugzilla #1731.

I'm checking this in to 3.0 so it can hit the build farm and flush out
any problems with other architectures.  With a bit of luck this should
go in to Samba 3.0.8.