Visual Studio Projects: Build Cleanup for Initial VS2026 Support

- Cleanup build details and provide initial detection support for
  building Visual Studio 2026.
- Automatically leverage the v141 Visual Studio platform Toolset if
  it is installed.  This avoids failing build attempts when windows_build
  hasn't yet been updated to support the frequently changing VS2022
  or VS2026 build components.
- Fix pdp11.vcproj to avoid warning when project is converted.
- Fix trivial compiler warnings in alpha_cpu.c and hp_tapelib.c

Visual Studio Projects/ConvertToV141Project.ps1

@@ -0,0 +1,96 @@
+# This script converts Visual Studio 2022 and 2026 upgraded VS2008 projects to produce 
+# VS2022 or VS2026 projects that will build executables that will link against Visual 
+# Studio 2017 libraries which are stable in the windows_build repo.
+#
+#$SDK = $env:WindowsSDKVersion
+param(
+    [string]$Solution
+    )
+$changedProjects = 0
+$changedSolution = 0
+$SDK = "10.0.26100.0\"
+$SDK = $SDK.Replace("\","")
+$solutionFile = $Solution
+$solutionPath = Split-Path -Path $solutionFile -Parent
+if (-not $solutionPath.Contains('\'))
+{
+    $solutionPath = "."
+}
+if (-not (Test-Path -Path $solutionFile -PathType Any)) {if (-not (Get-Item -Path $solutionFile -ErrorAction Ignore)) {Write-Host "No such file: $solutionFile"; }}
+$solution = Get-Content -Path $solutionFile -Raw
+$startingSolution = $Solution
+if ($solution -match 'Project\("{([0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12})}"\) = "BuildROMs", "BuildROMs.[a-z]*", "{([0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12})}"')
+{
+    $BuildROMsGUID = $($Matches[2])
+}
+$Projects = [Regex]::Matches($solution, '(?sm)}"\) = "(?<project>.*?)", "(?<file>.*?)"')
+if ($solution.Contains(".vcproj"))
+{
+    Write-Host "Attempting to fix Solution file which wasn't completely migrated:"
+    Write-Host $solutionFile
+}
+$dependencyPattern = "(?sm)\s\sProjectSection\(ProjectDependencies\) \= postProject.*?({.*?}).*?EndProjectSection"
+$solution = $solution -replace $dependencyPattern, ""
+$solution = $solution -replace ".vcproj", ".vcxproj"
+
+if (-not $solution.Contains("GlobalSection(ExtensibilityGlobals)"))
+{
+    $solution = $solution.Replace(
+"EndGlobal
+",
+"	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {$(New-Guid)}
+	EndGlobalSection
+EndGlobal
+")
+
+    $solution = $solution.Replace("Format Version 10.00", "Format Version 12.00")
+    $solution = $solution.Replace("Visual C++ Express 2008", "Visual Studio Version 17
+VisualStudioVersion = 17.14.36705.20 d17.14
+MinimumVisualStudioVersion = 10.0.40219.1")
+}
+ForEach ($Project in $Projects)
+{
+    $projFile = $solutionPath + "\" + $($Project.Groups['file'].Value).Replace(".vcproj", ".vcxproj")
+    if (-not (Test-Path -Path $ProjFile -PathType Any)) {if (-not (Get-Item -Path $ProjFile -ErrorAction Ignore)) {Write-Host "No such file: $ProjFile"; continue; }}
+    $projString  =  Get-Content -Path $projFile -Raw
+    $startingProjString = $projString
+    if ($projString.Contains("<WindowsTargetPlatformVersion>")) {Write-Host "$projFile - already converted"; continue; }
+    $projString = $projString.Replace(
+"<Keyword>Win32Proj</Keyword>
+", 
+"<Keyword>Win32Proj</Keyword> 
+    <WindowsTargetPlatformVersion>$SDK</WindowsTargetPlatformVersion>
+")
+    $projString = $projString.Replace("<PlatformToolset>v143</PlatformToolset>","<PlatformToolset>v141</PlatformToolset>")
+    $projString = $projString.Replace("<PlatformToolset>v144</PlatformToolset>","<PlatformToolset>v141</PlatformToolset>")
+    $projString = $projString.Replace("<PlatformToolset>v145</PlatformToolset>","<PlatformToolset>v141</PlatformToolset>")
+    $projString = $projString.Replace(
+' Label="LocalAppDataPlatform" />
+  ',' Label="LocalAppDataPlatform" />
+    <Import Project="simh.props" />
+  ')
+    if (-not $projString.Contains($BuildROMsGUID))
+    {
+        $ProjString = $ProjString.Replace(
+'  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />',
+('  <ItemGroup>
+    <ProjectReference Include="BuildROMs.vcxproj">
+      <Project>{' + $BuildROMsGUID.ToLower() + '}</Project>
+      <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />'))
+    }
+    if (-not ($projString -ceq $startingProjString))
+    {
+        $projString | Out-File -Force -FilePath "$projFile" -Encoding utf8
+        $changedProjects = $changedProjects + 1
+    }
+}
+if (-not ($solution -ceq $startingSolution))
+{
+    $solution | Out-File -Force -FilePath "$solutionFile" -Encoding utf8
+    $changedSolution = 1
+}
+Write-Host "Projects Changed: $changedProjects  Solution Changed: $changedSolution"