cxxll::pg_testdb test case: Compatibility with PostgreSQL 9.3
expat_source::malformed: Fix error message generation

XML_GetCurrentByteIndex can return a negative value.
The what_ member needs to be updated even in that case.
cxxll::fd_handle: Add wrappers for socket(), bind(), getsockname()

Currently used in a test case only.
cxxll::url_source: Properly report connection failure
Merge branch 'master' into postgresql-extension