Eliminate GCC signed/unsigned warnings related to encodings: The
encoding in the RFB protocol has always been signed, and signed values
are also used in the specification (ie DesktopName = -307 etc). In the
code, however, unsigned types were used in a number of places, but not
all, which causes warnings. This patch fixes the problem by switching
to signed values everywhere.
git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@3968 3789f03b-4d11-0410-bbf8-ca57d06f2519