GDBMI debugger: prevent endless loops

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@47145 4005530d-fff6-0310-9dd1-cebe43e6787f
SynEdit: prevent dangling pointer

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@47146 4005530d-fff6-0310-9dd1-cebe43e6787f