[WIP] Don't use quoting

Execute clang on Windows directly for NDK r19+, avoids trouble with
having to quote spaces in the path so that NDK .cmd scripts don't fail.

Author: grendello

src/Xamarin.Android.Build.Tasks/Utilities/NdkTools/NdkTools.cs

@@ -216,16 +216,18 @@ protected virtual string GetPlatformLibPath (AndroidTargetArch arch, int apiLeve
 		{
 			string? executablePath = null;
 			if (IsWindows) {
-				string toolDir = Path.GetDirectoryName (toolPath);
-				executablePath = Path.Combine (toolDir, MonoAndroidHelper.GetExecutablePath (toolDir, Path.GetFileName (toolPath)));
-
-				if (String.Compare (Path.GetExtension (executablePath), ".cmd", StringComparison.Ordinal) == 0 && executablePath.IndexOf (' ') >= 0) {
-					// NDK has CMD scripts to execute the compilers on Windows, but the scripts do not quote spaces in the command path properly, we need to do
-					// it for them here or e.g. mkbundle will fail:
-					//
-					//  [CC] "C:\a\_work\1\s\bin\TestRelease\temp\SDK Ümläüts\ndk\toolchains\llvm\prebuilt\windows-x86_64\bin\armv7a-linux-androideabi16-clang.CMD" -c -D__ANDROID_API__=16 -DANDROID -o obj\Release\bundles\armeabi-v7a\temp.o -I "C:\a\_work\1\s\bin\TestRelease\temp\SDK Ümläüts\ndk\sysroot\usr\include\arm-linux-androideabi" -I "C:\a\_work\1\s\bin\TestRelease\temp\SDK Ümläüts\ndk\sysroot\usr\include" obj\Release\bundles\armeabi-v7a\temp.c (TaskId:181)
-					// [cc stderr] 'C:\a\_work\1\s\bin\TestRelease\temp\SDK' is not recognized as an internal or external command, (TaskId:181)
-					executablePath = executablePath.Replace (" ", "\\ ");
+				// We can't just use `File.Exists (toolPath)` since the Windows NDK contains extension-less
+				// Unix shell scripts which would fail to work if an attempt to execute them would be made.
+				//
+				// Also, the NDK r19+ workaround (see NdkToolsWithClangWithPlatforms.ctor) will cause `toolPath`
+				// here to end with .exe when looking for the compiler and we can save some time by not letting
+				// `MonoAndroidHelper.GetExecutablePath` iterate over all %PATHEXT% extensions only to return the
+				// original tool name
+				if (Path.HasExtension (toolPath) && File.Exists (toolPath)) {
+					executablePath = toolPath;
+				} else {
+					string toolDir = Path.GetDirectoryName (toolPath);
+					executablePath = Path.Combine (toolDir, MonoAndroidHelper.GetExecutablePath (toolDir, Path.GetFileName (toolPath)));
 				}
 			} else if (File.Exists (toolPath)) {
 				executablePath = toolPath;

src/Xamarin.Android.Build.Tasks/Utilities/NdkTools/WithClang.cs

@@ -10,6 +10,9 @@ abstract class NdkToolsWithClang : NdkTools
 	{
 		protected string UnifiedHeadersDirPath { get; }
 
+		// See NdkToolsWithClangWithPlatforms.ctor for explanation
+		protected bool NeedClangWorkaround { get; set; }
+
 		protected NdkToolsWithClang (string androidNdkPath, NdkVersion version, TaskLoggingHelper? log)
 			: base (androidNdkPath, version, log)
 		{
@@ -46,7 +49,10 @@ public override string GetToolPath (NdkToolKind kind, AndroidTargetArch arch, in
 			string toolName = GetToolName (kind);
 
 			if (kind == NdkToolKind.CompilerC || kind == NdkToolKind.CompilerCPlusPlus) {
-				toolName = $"{GetCompilerTriple (arch)}{apiLevel}-{toolName}";
+				if (!NeedClangWorkaround) {
+					// See NdkToolsWithClangWithPlatforms.ctor for explanation
+					toolName = $"{GetCompilerTriple (arch)}{apiLevel}-{toolName}";
+				}
 			} else {
 				toolName = $"{GetArchTriple (arch)}-{toolName}";
 			}

src/Xamarin.Android.Build.Tasks/Utilities/NdkTools/WithClangWithPlatforms.cs

@@ -7,13 +7,11 @@ namespace Xamarin.Android.Tasks
 {
 	class NdkToolsWithClangWithPlatforms : NdkToolsWithClang
 	{
-		bool needClangWorkaround;
-
 		public NdkToolsWithClangWithPlatforms (string androidNdkPath, NdkVersion version, TaskLoggingHelper? log)
 			: base (androidNdkPath, version, log)
 		{
-			needClangWorkaround = IsWindows && Version.Main.Major == 19 && Version.Main.Minor < 2;
-			if (needClangWorkaround) {
+			NeedClangWorkaround = IsWindows && Version.Main.Major >= 19;
+			if (NeedClangWorkaround) {
 				//
 				// NDK r19 bug (fixed in r19c).
 				//
@@ -38,13 +36,19 @@ public NdkToolsWithClangWithPlatforms (string androidNdkPath, NdkVersion version
 				//
 				// The code below tries to rectify the situation by special-casing the compiler tool handling to
 				// return path to the actual .exe instead of the CMD.
+				//
+				// Despite the above issue having been fixed in NDK r19c, the CMD scripts in question have another issue -
+				// they don't work well with paths that have spaces in them. That means we either need to quote the paths
+				// ourselves, or invoke the compilers directly.  The latter option seems to be the better one.
+				//
 				NdkToolNames[NdkToolKind.CompilerC] = "clang.exe";
+				NdkToolNames[NdkToolKind.CompilerCPlusPlus] = "clang++.exe";
 			}
 		}
 
 		public override string GetCompilerTargetParameters (AndroidTargetArch arch, int apiLevel, bool forCPlusPlus = false)
 		{
-			if (!needClangWorkaround) {
+			if (!NeedClangWorkaround) {
 				return base.GetCompilerTargetParameters (arch, apiLevel, forCPlusPlus);
 			}