Detect posix_fallocate at configure time

Testing feature macros is not enough for uclibc. Fixes build of the built-in
sqlite3 with uclibc <= 0.9.33.2. Later versions will have posix_fallocate().

Change-Id: I918a52777ac63624635802221effc6b86fa2269c
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
Fix evaluation of SQLite driver options

Ensure that the options, which are passed to the SQLite driver, are
evaluated in the correct order and do not overwrite each other.
According to http://www.sqlite.org/c3ref/open.html the
SQLITE_OPEN_READONLY and (SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE) are
mutual exclusive, but SQLITE_OPEN_URI can be combined with both of them.

Task-number: QTBUG-35186
[ChangeLog][QtSql][QSQLITE] Fixed evaluation of driver options
Change-Id: I8e74fe1ce43b9118b15f7b13fc71670bdcd73f68
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
Fix compilation of OCI driver

Add missing feature enum in switch statement to
avoid warning that would lead to compilation error
when compiled with -Wall.

Task-number: QTBUG-34794
Change-Id: Ia2f70f27ecbb7a7dfc9d36d261103ff49b6c5e4b
[ChangeLog][QtSql][QOCI] Fix compilation
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
Support custom port number in IBASE SQL driver

Let the IBASE SQL driver use the custom port number
that is set via QSqlDatabase::setPort().

Task-number: QTBUG-33345
Change-Id: Ib55b32c8a318d82038d66e8645b416e36dad3edf
[ChangeLog][QtSql][QIBASE] Support custom port number
Reviewed-by: Mark Brand <mabrand@mabrand.nl>