Remove use of file absolute paths.

An absolute path is derived from a relative path by
appending the value of "user.dir" to it. "user.dir" is
populated by the VM by calling getcwd(3). All apps
forked from zygote end up with a "user.dir" (and a current
working directory) value of "/".

This, along with change 417621196b855 (which prevents
"user.dir" from being changed by apps) will make file handling
a lot more consistent. In particular 417621196 ensures that

- The output of getAbsolutePath can never change for a given
  relative path.
- File.getPath() and File.getAbsolutePath() become interchangeable
  wrt. lower level (Libcore.os) APIs.

Change-Id: I5598a2b1c5de65b59d69324f98656ffe031290f0
3 files changed