* gdb.texinfo (Copying): delete this node and references to it;

* gdb.texinfo (Copying): delete this node and references to it;
RMS says this manual need not carry GPL. (passim): Improvements
from last round at FSF, largely due to Ian Taylor review, and
minor formatting improvements.

* gdbinv-s.texi (passim): Improvements from last round at FSF,
largely due to Ian Taylor review. (Debug Session): minor edits to
new text.