Change JniInvocation default to libart.so

In particular, this makes dalvikvm host invocations on
host use ART instead of dalvik.

Change-Id: I2220c529434f5c7c07687ca2aaa442f7dbcc9733
Adds a libc++ version of libnativehelper

Change-Id: I9e91ac31f4c2d7b7ba7c2ed0fbdce1f2b01355e5
Don't build libc++ libs for ub branches

Change-Id: I8fe4d0a13eef77b19f3c29180cce26aa3bf90abe
Make libnativehelper C++ library agnostic and remove libnativehelper_libc++.

Change-Id: Ib5510add3337992dc2a99affe671a01d39782237
TEMP_FAILURE_RETRY() requires errno.h

Fixes compiler error about not finding errno when art is compiled for the host
using libc++.

Change-Id: Ib2bcd6b230dbb05e7c5306d5d12e25483202b457
Host multilib for multilib ART support.

Change-Id: I375bff0f7f242f48fc2674c1d502501ff2197396
Add reset to ScopedFd.

The implementation follows the pattern of UniquePtr.

Change-Id: I761c89d393b610600e863e223f2545ded1fde441
Fixing PrintWriter not being disposed

When there is an exception being thrown, the getStackTrace method of
JNIHelp will initialize a PrintWriter to print the exception message.
But the instance of the PrintWriter will not be disposed, because
PrintWriter will hold the string reference, and finally the local
reference table of VM will overflow. Then system will crash.

The change disposes the PrintWriter from the local reference table
to prevent the overflow.

Change-Id: Ie8dcb3d941034e6e1f480196373189f2d152cf79