[libFuzzer] Don't prefix absolute paths in fuchsia.

The ExecuteCommand function in fuchsia used to prefix the
getOutputFile for each command run with the artifact_prefix flag if
it was available, because fuchsia components don't have a writable working
directory. However, if a file with a global path is provided, fuchsia
should honor that.

An example of this is using the global /tmp directory to store stuff.
In fuchsia it ended up being translated to data///tmp, whereas we want
to make sure it is using /tmp (which is available to components using the
isolated-temp feature).

To test this I made the change, compiled fuchsia with this toolchain and
ran a fuzzer with the -fork=1 flag (that mode makes use of the /tmp
directory). I also tested that normal fuzzing workflow was not affected
by this.

Author: charco (Marco Vanotti)
Differential Revision: https://reviews.llvm.org/D68774

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@374612 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed