Add some error checking and clean out some cruft.

Error checking #1: When a cached dex file can't be created, do extra
analysis to figure out (and report) why.

Error checking #2: When opening classpath entries, become sensitive
to the file extension, only trying to open files with the right
extensions and complaining explicitly if it's unrecognized.

Cruft cleaning: We've never supported finding class files in directory
hierarchies in Dalvik. Fix some related comments and clean out some
code that tried (in vain) to implement a piece of that.

Bug: 4523201
Change-Id: I05b7a8570f147955cd62229fca72b50d36703752
4 files changed