Release libpng version 1.6.37

Release libpng version 1.6.36

Run autogen.sh

[libpng16] Imported from libpng-1.6.35beta01.tar

[libpng16] Imported from libpng-1.6.34.tar

[libpng16] Imported from libpng-1.6.33.tar

[libpng15] Imported from libpng-1.5.30.tar

 [libpng14] Imported from libpng-1.4.22.tar

[libpng12] Imported from libpng-1.2.59.tar

[libpng16] Imported from libpng-1.6.33rc02.tar