release-windows-packages: add command line options --tarversion to specify different tar ball version

You might overrun the 1024-character fixed-size string URL by copying the
return value of constData without checking the length.

We now use a QByteArray instance instead of a fixed char buffer.

BUG:418970
FIXED-IN:2.31.1 (KDE releases 20.04.1)

The testcase used to fix this issue is located at test/import/cxx/comment-class.h.

CCBUG:418970

Conflicts:
	CMakeLists.txt

llvm changes api on each major release.

CCBUG:419202

This reverts commit a5ef27d1.

The reason for this commit was, that some dot installations do not
support 'png' format, which was fixed now.

CCBUG:419202

This should fix related warnings on KDE CI.

CCBUG:419202

This should fix 'dot' errors like 'Format: "png" not recognized....'

CCBUG:419202

This fixes the following warning on KDE CI:

Generating docs for file umbrello/codeimport/idlimport.cpp warning:
Included by graph for 'debug_utils.h' not generated, too many nodes.
Consider increasing DOT_GRAPH_MAX_NODES.

The detection of supported dot versions (>= 1.8.10) seems to not work
correctly.

CCBUG:419202

CCBUG:419202

CCBUG:419202

In case of conflict in i18n, keep the version of the branch "ours"
To resolve a particular conflict, "git checkout --ours path/to/file.desktop"

FindDoxygen.cmake uses the IN_LIST operator, for which it is necessary
to specify the named policy.

This bug was reported by Jonathan Riddell.

CCBUG:419202

Conflicts:
	CMakeLists.txt

For easier troubleshooting, a status line is now displayed if
qhelpgenerator was found.

A new cmake option BUILD_APIDOC has been added (default:on), which
can be used to disable the creation of api doc if this is not desired.

BUG:419202
FIXED-IN:2.30.90 (KDE releases 20.03.90)