Windows: Fix build issue with newer Visual Studio

Encountered this error after updates to Visual Studio.

5>rarpch.cpp

5>c:\program files (x86)\windows kits\10\include\10.0.22621.0\um\winnt.h(2535): error C2338: Windows headers require the default packing option. Changing this can lead to memory corruption. This diagnostic can be disabled by building with WINDOWS_IGNORE_PACKING_MISMATCH defined.

It seems that libclamunrar VS project file was set to 4-byte struct
member alignment. Changing this to "Default" fixes the issue.

win32/libclamunrar.vcxproj

@@ -100,7 +100,7 @@
       <ExceptionHandling>Sync</ExceptionHandling>
       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
-      <StructMemberAlignment>4Bytes</StructMemberAlignment>
+      <StructMemberAlignment>Default</StructMemberAlignment>
       <RuntimeTypeInfo>false</RuntimeTypeInfo>
       <PrecompiledHeader>Use</PrecompiledHeader>
       <PrecompiledHeaderFile>rar.hpp</PrecompiledHeaderFile>
@@ -131,7 +131,7 @@
       <ExceptionHandling>Sync</ExceptionHandling>
       <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
-      <StructMemberAlignment>4Bytes</StructMemberAlignment>
+      <StructMemberAlignment>Default</StructMemberAlignment>
       <RuntimeTypeInfo>false</RuntimeTypeInfo>
       <PrecompiledHeader>Use</PrecompiledHeader>
       <PrecompiledHeaderFile>rar.hpp</PrecompiledHeaderFile>
@@ -162,7 +162,7 @@
       <MinimalRebuild>false</MinimalRebuild>
       <ExceptionHandling>Sync</ExceptionHandling>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
-      <StructMemberAlignment>4Bytes</StructMemberAlignment>
+      <StructMemberAlignment>Default</StructMemberAlignment>
       <BufferSecurityCheck>true</BufferSecurityCheck>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <EnableEnhancedInstructionSet>NoExtensions</EnableEnhancedInstructionSet>
@@ -204,7 +204,7 @@
       <MinimalRebuild>false</MinimalRebuild>
       <ExceptionHandling>Sync</ExceptionHandling>
       <RuntimeLibrary>MultiThreadedDebug</RuntimeLibrary>
-      <StructMemberAlignment>4Bytes</StructMemberAlignment>
+      <StructMemberAlignment>Default</StructMemberAlignment>
       <BufferSecurityCheck>true</BufferSecurityCheck>
       <FunctionLevelLinking>true</FunctionLevelLinking>
       <RuntimeTypeInfo>false</RuntimeTypeInfo>