[Update] libpng version 1.6.37

* Merge libpng version 1.6.37: commit 'a40189cf881e9f0db80511c382292a5604c3c3d1'
* Suppress warning when comparing between signed and unsigned values
* Remove unneeded files
* Add arm source file in BUILD.gn

* Tested png, user report 89106481223

Fixed: 87754

Change-Id: Icc5d5754388356c6244770178facd03a36bfb1b4