add arm64 config for mpfr

Author: lkeegan

build.ps1

@@ -820,7 +820,13 @@ $mpirLib = Resolve-LibraryPath @("mpir.lib", "lib_mpir_gc.lib", "libmpir*.lib")
 Invoke-GitClonePinnedCommit "https://github.com/BrianGladman/mpfr.git" $env:MPFR_MSVC_VERSION "mpfr"
 $mpfrBuildDir = Resolve-ExistingDirectory @("mpfr\build.vs22", "mpfr\build.vs19")
 Push-Location $mpfrBuildDir
-msbuild.exe /m /p:Platform=$msvcPlatform /p:Configuration=Release "lib_mpfr\lib_mpfr.vcxproj"
+$mpfrProject = "lib_mpfr\lib_mpfr.vcxproj"
+if ($msvcPlatform -eq "ARM64") {
+  $mpfrProjectContents = Get-Content -Path $mpfrProject -Raw
+  $mpfrProjectContents = $mpfrProjectContents.Replace("x64", "ARM64").Replace("X64", "ARM64")
+  Set-Content -Path $mpfrProject -Value $mpfrProjectContents -Encoding utf8
+}
+msbuild.exe /m /p:Platform=$msvcPlatform /p:Configuration=Release $mpfrProject
 $mpfrReleaseDir = Resolve-ExistingDirectory ($msvcPlatformDirCandidates | ForEach-Object { "lib\$_\Release" })
 Copy-Item -Path (Join-Path $mpfrReleaseDir "*.lib") -Destination $installLibDir -Force
 Copy-Item -Path (Join-Path $mpfrReleaseDir "*.pdb") -Destination $installLibDir -Force -ErrorAction SilentlyContinue