Update libpng to version 1.6.3

(cherry picked from commit ca2bf81b02c99afa2e76b3b2c6eb232c239221e0)

Change-Id: I313493fa630be9812e503ae24820b2923ed717f3
Tweak makefile

 Fix broken builds on non-NEON devices
 Use runtime NEON detection

(cherry picked from commit 825dd0c95ae50ed3247c4593c0808d062aae09ec)

Change-Id: I9c42191b065a6f4e40c6ebff7124044fd073d329
Use arch-specific flags to fix multilib build.

(cherry picked from commit fa6268cfac65636ae5aa8740ca9b3e5c4b77e1ca)

Change-Id: Ie11944529182f3ea0da19313474a843434efeed3
Turn off SLP vectorization until http://llvm.org/PR19472 is fixed.

Change-Id: I77166548871181b8e327e4ece18e1d5ce0b346bd
Use -no-integrated-as on Darwin.

Change-Id: Ib096eec1da985611882bc6c228a803b15c8d668c
Update libpng from 1.6.3 to 1.6.10

Change-Id: I76e81e7fd267d15991cd342c5caeb2fe77964ebf
libpng 1.6.10 enable NEON Optimizations

Change-Id: Iba40175651b4e384dd1f221113dcae46f711b0aa
Revert "libpng 1.6.10 enable NEON Optimizations"

breaks builds, more investigation needed

This reverts commit 61c00d54ff8b296a449a1810d2acc87262dfc314.

Change-Id: I5b607b8316fb3a61bc67d4077b0b7d5ceb9ea2d6
libpng - enable neon support

Neon support failed on aosp_arm-eng because that
build didn't have NEON support but yet NEON flags
were applied unconditionally.

This change conditions NEON flags on ARCH_ARM_HAVE_NEON.

Change-Id: Id8dbf98e6f2bdd85857ac0836fde1b4c6ff37cc5
libpng NEON enablement for ARM64

Android.mk added ARM64 flags
pngpriv.h - gcc aarch64 __ARM_NEON support which enables intrinsics

Discussion http://comments.gmane.org/gmane.comp.graphics.png.devel/6601

Patches on libpng16 branch
http://sourceforge.net/p/libpng/code/ci/c45f1223cb5136edccd05ada1ca4498ed01c4087/
http://sourceforge.net/p/libpng/code/ci/fc932f7b03c1198fb66b35e5801a0d365f9a6e99/

Change-Id: Ifb64c4624a1b05c40d873b1b4c03ecda8de2d1b8