COMP: Added missing png_get_uint_31 name mangling
COMP: Added missing png_get_uint_31 name mangling

The itk mangling header file was not up to date with the png library,
resulting in all symbols being mangled except for png_get_uint_31.
This issue was described and solved by Niels Dekker:
http://public.kitware.com/pipermail/insight-developers/2017-April/025158.html

Change-Id: I37c8fe14a6ebf7ca6ec3cfdc10f4d86156e57337

malaterre/ITK,InsightSoftwareConsortium/ITK,hjmjohnson/ITK,fbudin69500/ITK,richardbeare/ITK,fbudin69500/ITK,Kitware/ITK,vfonov/ITK,stnava/ITK,LucasGandel/ITK,spinicist/ITK,richardbeare/ITK,PlutoniumHeart/ITK,BRAINSia/ITK,BRAINSia/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,PlutoniumHeart/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,spinicist/ITK,hjmjohnson/ITK,BRAINSia/ITK,malaterre/ITK,fbudin69500/ITK,malaterre/ITK,PlutoniumHeart/ITK,thewtex/ITK,blowekamp/ITK,stnava/ITK,BRAINSia/ITK,fbudin69500/ITK,vfonov/ITK,vfonov/ITK,blowekamp/ITK,richardbeare/ITK,stnava/ITK,hjmjohnson/ITK,Kitware/ITK,LucasGandel/ITK,BRAINSia/ITK,PlutoniumHeart/ITK,spinicist/ITK,spinicist/ITK,stnava/ITK,fbudin69500/ITK,PlutoniumHeart/ITK,LucasGandel/ITK,PlutoniumHeart/ITK,blowekamp/ITK,PlutoniumHeart/ITK,stnava/ITK,InsightSoftwareConsortium/ITK,fbudin69500/ITK,spinicist/ITK,thewtex/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,malaterre/ITK,blowekamp/ITK,thewtex/ITK,LucasGandel/ITK,stnava/ITK,spinicist/ITK,LucasGandel/ITK,vfonov/ITK,malaterre/ITK,blowekamp/ITK,PlutoniumHeart/ITK,richardbeare/ITK,stnava/ITK,malaterre/ITK,richardbeare/ITK,malaterre/ITK,malaterre/ITK,spinicist/ITK,vfonov/ITK,hjmjohnson/ITK,Kitware/ITK,BRAINSia/ITK,LucasGandel/ITK,blowekamp/ITK,InsightSoftwareConsortium/ITK,LucasGandel/ITK,stnava/ITK,thewtex/ITK,hjmjohnson/ITK,blowekamp/ITK,fbudin69500/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,hjmjohnson/ITK,fbudin69500/ITK,Kitware/ITK,thewtex/ITK,LucasGandel/ITK,vfonov/ITK,stnava/ITK,spinicist/ITK,blowekamp/ITK,thewtex/ITK,Kitware/ITK,hjmjohnson/ITK,richardbeare/ITK,Kitware/ITK,Kitware/ITK,spinicist/ITK