Build stuff with /Gw

It's not very useful, but it doesn't appear to have any downsides.

aegisub/build/icu/icu.vcxproj

@@ -13,7 +13,7 @@
 
   <PropertyGroup Label="ConfigArgs">
     <CfgDebug Condition="'$(Configuration)' == 'Debug'">--enable-debug --disable-release CFLAGS=-MDd CXXFLAGS=-MDd</CfgDebug>
-    <CfgDebug Condition="'$(Configuration)' == 'Release'">--disable-debug --enable-release CFLAGS=-MD CXXFLAGS=-MD</CfgDebug>
+    <CfgDebug Condition="'$(Configuration)' == 'Release'">--disable-debug --enable-release CFLAGS="-MD -Gw" CXXFLAGS="-MD -Gw"</CfgDebug>
     <CfgArgs>
       CC=cl
       CXX=cl

aegisub/build/standard-settings.props

@@ -59,6 +59,7 @@
 			<FunctionLevelLinking>true</FunctionLevelLinking>
 			<IntrinsicFunctions>true</IntrinsicFunctions>
 			<PreprocessorDefinitions>NDEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+			<AdditionalOptions>/Gw %(AdditionalOptions)</AdditionalOptions>
 		</ClCompile>
 		<Link>
 			<EnableCOMDATFolding>true</EnableCOMDATFolding>