Fix QTemporaryFile regressions and new found issues

Fix QTemporaryFile regressions and new found issues

With this change, the file template is always processed in original
QString format. Trying to generate native paths before adding a missing
placeholder mask could change the meaning of templates, such as "." and
"..", which are now tested to mean "..XXXXXX" and "...XXXXXX",
respectively.

After ensuring the template includes a placeholder mask, the path is
converted to a native *absolute* file path and the mask is sought for
again. On Windows, native paths were already absolute. On Symbian, we'd
need at least a clean path, as "." and ",," are not natively understood.

There is a requirement that the placeholder mask /XXXXXX+/ makes it
through this conversion unaltered, which relaxes prior requirements on
*nix platforms. On Windows and Symbian the conversion is under Qt's
control and not user-configurable.

Reviewed-by: Shane Kearns
(cherry picked from commit 401722ef9e6fe79bd41f9d5f79668f5c4997c8e6)

Conflicts:

	tests/auto/qtemporaryfile/tst_qtemporaryfile.cpp

Change-Id: Iac823881c865adf0931dc4f429c6c1ef135eeb56
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>