DO NOT MERGE Update libpng to 1.6.20

BUG:23265085
Change-Id: I28912577d10ea5bafd139c4ca1baf3b543bf36a9
diff --git a/projects/vstudio/pngvalid/pngvalid.vcxproj b/projects/vstudio/pngvalid/pngvalid.vcxproj
new file mode 100644
index 0000000..07cf241
--- /dev/null
+++ b/projects/vstudio/pngvalid/pngvalid.vcxproj
@@ -0,0 +1,219 @@
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+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
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+    <ProjectConfiguration Include="Release Library|Win32">
+      <Configuration>Release Library</Configuration>
+      <Platform>Win32</Platform>
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+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
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+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{9B36B6FE-7FC0-434F-A71F-BBEF8099F1D8}</ProjectGuid>
+    <Keyword>Win32Proj</Keyword>
+    <RootNamespace>pngvalid</RootNamespace>
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+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
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+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'" Label="Configuration">
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+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release Library|Win32'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <CharacterSet>Unicode</CharacterSet>
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+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
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+  <PropertyGroup Label="UserMacros" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <LinkIncremental>false</LinkIncremental>
+    <CustomBuildAfterTargets />
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+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug Library|Win32'">
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+    <ClCompile>
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+      <WarningLevel>Level4</WarningLevel>
+      <MinimalRebuild>false</MinimalRebuild>
+      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
+      <Optimization>Disabled</Optimization>
+      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
+      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;PNG_USE_DLL;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <AdditionalIncludeDirectories>$(ZLibSrcDir);..\..\..\scripts;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
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+      <StringPooling>true</StringPooling>
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+      <BrowseInformation>true</BrowseInformation>
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+    <Link>
+      <SubSystem>Console</SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+      <AdditionalDependencies>libpng16.lib;zlib.lib</AdditionalDependencies>
+      <AdditionalLibraryDirectories>$(OutDir)</AdditionalLibraryDirectories>
+    </Link>
+    <CustomBuildStep>
+      <Message>Executing PNG validation program</Message>
+      <Command>"$(OutDir)pngvalid.exe" --touch "$(IntDir)pngvalid.out"</Command>
+      <Outputs>$(IntDir)pngvalid.out</Outputs>
+      <Inputs>$(OutDir)pngvalid.exe</Inputs>
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+    </Link>
+    <CustomBuildStep>
+      <Message>Executing PNG validation program</Message>
+      <Command>"$(OutDir)pngvalid.exe" --touch "$(IntDir)pngvalid.out"</Command>
+      <Outputs>$(IntDir)pngvalid.out</Outputs>
+      <Inputs>$(OutDir)pngvalid.exe</Inputs>
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+      <OptimizeReferences>true</OptimizeReferences>
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+      <AdditionalLibraryDirectories>$(OutDir)</AdditionalLibraryDirectories>
+      <LinkTimeCodeGeneration>UseLinkTimeCodeGeneration</LinkTimeCodeGeneration>
+    </Link>
+    <CustomBuildStep>
+      <Message>Executing PNG validation program</Message>
+      <Command>"$(OutDir)pngvalid.exe" --touch "$(IntDir)pngvalid.out"</Command>
+      <Outputs>$(IntDir)pngvalid.out</Outputs>
+      <Inputs>$(OutDir)pngvalid.exe</Inputs>
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+      <DisableSpecificWarnings>4996;4127</DisableSpecificWarnings>
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+      <FloatingPointExceptions>false</FloatingPointExceptions>
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+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+      <OptimizeReferences>true</OptimizeReferences>
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+      <AdditionalLibraryDirectories>$(OutDir)</AdditionalLibraryDirectories>
+      <LinkTimeCodeGeneration>UseLinkTimeCodeGeneration</LinkTimeCodeGeneration>
+    </Link>
+    <CustomBuildStep>
+      <Message>Executing PNG validation program</Message>
+      <Command>"$(OutDir)pngvalid.exe" --touch "$(IntDir)pngvalid.out"</Command>
+      <Outputs>$(IntDir)pngvalid.out</Outputs>
+      <Inputs>$(OutDir)pngvalid.exe</Inputs>
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