CppEditor: Make the string auto-string splitting less eager
CppEditor: Make the string auto-string splitting less eager

It was already triggering when inserting a new line in a .qdoc file
such as /data/dev/creator-3.3/doc/src/howto/creator-help.qdoc. In that
case, tokens() was empty, but prevState == 5 (T_DOXY_COMMENT).

Change-Id: I445d4df14182b0b536181588a224917a814a3f7f
Reviewed-by: Eike Ziller <c142da16c73a95a82d35191bcc55b22835617128@theqtcompany.com>
Reviewed-by: hjk <f81b91af79013637d070c18d38a75b90eaae8ba3@nokiamail.com>

danimo/qt-creator,AltarBeastiful/qt-creator,Distrotech/qtcreator,xianian/qt-creator,Distrotech/qtcreator,Distrotech/qtcreator,martyone/sailfish-qtcreator,AltarBeastiful/qt-creator,Distrotech/qtcreator,AltarBeastiful/qt-creator,danimo/qt-creator,martyone/sailfish-qtcreator,danimo/qt-creator,amyvmiwei/qt-creator,AltarBeastiful/qt-creator,danimo/qt-creator,kuba1/qtcreator,amyvmiwei/qt-creator,amyvmiwei/qt-creator,xianian/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,farseerri/git_code,xianian/qt-creator,Distrotech/qtcreator,amyvmiwei/qt-creator,xianian/qt-creator,danimo/qt-creator,martyone/sailfish-qtcreator,xianian/qt-creator,amyvmiwei/qt-creator,kuba1/qtcreator,Distrotech/qtcreator,danimo/qt-creator,farseerri/git_code,xianian/qt-creator,farseerri/git_code,kuba1/qtcreator,kuba1/qtcreator,farseerri/git_code,amyvmiwei/qt-creator,AltarBeastiful/qt-creator,xianian/qt-creator,kuba1/qtcreator,AltarBeastiful/qt-creator,AltarBeastiful/qt-creator,martyone/sailfish-qtcreator,AltarBeastiful/qt-creator,danimo/qt-creator,kuba1/qtcreator,farseerri/git_code,danimo/qt-creator,amyvmiwei/qt-creator,martyone/sailfish-qtcreator,farseerri/git_code,xianian/qt-creator,farseerri/git_code,martyone/sailfish-qtcreator,martyone/sailfish-qtcreator,Distrotech/qtcreator,kuba1/qtcreator,farseerri/git_code,kuba1/qtcreator,martyone/sailfish-qtcreator,danimo/qt-creator,kuba1/qtcreator,amyvmiwei/qt-creator