png-release 2019-03-20 (b422a024)

Code extracted from:

    https://gitlab.kitware.com/third-party/png.git

at commit b422a0240b91b04ca94ae84291d6ff1a064b3228 (for/vtk-old-20190320-1.6.29).

CMakeLists.txt

@@ -31,6 +31,11 @@ if (WIN32)
   endif ()
 endif ()
 
+add_definitions(-DPNG_ARM_NEON_OPT=0)
+add_definitions(-DPNG_MIPS_MSA_OPT=0)
+add_definitions(-DPNG_POWERPC_VSX_OPT=0)
+add_definitions(-DPNG_INTEL_SSE_OPT=0)
+
 configure_file(
   "${CMAKE_CURRENT_SOURCE_DIR}/vtkpngConfig.h.in"
   "${CMAKE_CURRENT_BINARY_DIR}/vtkpngConfig.h")