Preventing caching of null authenticator

In some cases, e.g. when bad credentials are provided in an ftp URI,
QNetworkAccessAuthenticationManager::cacheCredentials is called with a
null authenticator. This authenticator should not be cached, because
it is useless, and leads to inconsistencies in the use of the cache

Task-number: QTBUG-40622
Change-Id: If2a0a422b915f268648f5eef1d68601446123371
Reviewed-by: Peter Hartmann <phartmann@blackberry.com>
qsql ibase: fix memory corruption due to LONG being 4 bytes in firebird.

As fb_types.h says, Firebird requires (S)LONG to be 32 bit, and it defines
SLONG to int. This leads to sqllen being 4, so qsql_ibase.cpp allocates
4 bytes... and was writing 8 bytes into it.

Fixed by checking sqllen, the same way QIBaseResult::gotoNext does.

Change-Id: Ie8680d32f98c354dfc8430b8efbfe95450556956
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
Add QMAKE_CFLAGS_XCB to xcb

Add QMAKE_CFLAGS_XCB to xcb-static,
needed for successfully building with -qt-xcb.
Add QMAKE_CFLAGS because some code gets built with the C compiler.
Also, this fixes a compile error
when xcb include is not in system include path.

Task-number: QTBUG-41129
Change-Id: I842ebe391a7a857e234becc451c33601fce9b07a
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>