GDB pretty printer using gdb.LazyString no longer works

With Qt Creator 16.0 and current master branch, LibreOffice's pretty-printers for e.g. the custom OUString string type no longer work.

This seems to be a problem with handling of gdb.Lazystring. I plan to submit a change to fix it.

Sample steps to reproduce:

1) Set up a LibreOffice development build as described at https://wiki.documentfoundation.org/Development

2) enable system GDB pretty printers in Qt Creator ("Edit" -> "Preferences" -> "Debugger" -> "GDB", check "Load System GDB pretty printers" checkbox)

3) set a breakpoint at some code location using OUString in the LibreOffice source code and start debugging

When that breakpoint is reached, the value of the OUString object isn't properly shown for the local variable or class member.

Printing it in the debugger log still works fine.

LibreOffice GDB pretty printer: https://git.libreoffice.org/core/+/e37b3c6c2e794222517f85007289ed52c605b2e5/solenv/gdb/libreoffice/sal.py

I'm not going into more detail regarding the exact steps to reproduce the setup, as I plan to submit a fix myself.