PR59161 make pretty printers always return strings
PR libstdc++/59161
* python/libstdcxx/v6/printers.py (StdListIteratorPrinter.to_string)
(StdSlistIteratorPrinter.to_string, StdVectorIteratorPrinter.to_string)
(StdRbtreeIteratorPrinter.to_string, StdDequeIteratorPrinter.to_string)
(StdDebugIteratorPrinter.to_string): Return string instead of
gdb.Value.
* testsuite/libstdc++-prettyprinters/59161.cc: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@243690 138bc75d-0d04-0410-961f-82ee72b054a4