Added XML output mode for dexdump.

Added XML output mode for dexdump.

This adds an output mode that looks similar to the "current.xml" we
generate for our public APIs.  There are a number of differences in
content.  The original ("plain") output has not been altered.

I pulled in the bad checksum handling change (internal 142686) since
it's small, has turned out to be useful, and might make the merge of
this to master slightly easier.

This also renames a buffer in the ongoing temp file variable saga.