Always use long description in full version string.

If we are on a tagged revision, the qtpdcom_full_version string is for example "1.3.3".

The docs say:

Library version with four fields followed by the commit hash. A trailing plus sign shows that uncommitted changes existed during the build. The hash is prefixed with a "g" to indicate that git is used as version control system. Example: "5.1.0.8.gea62937+".

So the commit has is always expected to be part of the string.