Strings: hardcode "\n" as the line separator

For android, it's already hardcoded in System.java

It was trying to use
System.getProperty("line.separator");
causing the class not to be compile-time initializable, causing
performance problems, see bug.

(cherry picked from commit 7ddf37c01b68ff9d2de3a9dcb637d2b962b442ef)

Bug: 28108158
Change-Id: I4f34ddf5c82232821df083993f36ab9d964ec98d
1 file changed