Fix renderscript issue on windows.

The code was quoting paths send to the command line (even though
it's not required since the exec tasks an array of args instead of
a single line). However if the paths end with a trailing file separator
then, on windows only, this had the effect of escaping the quote,
basically adding with the path:

"c:\foo\" -> c:\foo"

Change-Id: Ia77b6404e69fda8df457fd1a56478296ee455898