Use aot friendly interop in System.Diagnostics.Process (#28329)

Fixes dotnet/corert#5593

Author: jkotas

src/Common/src/Interop/Windows/advapi32/Interop.CreateProcessWithLogon.cs

@@ -16,13 +16,13 @@ internal static extern bool CreateProcessWithLogonW(
             string domain,
             IntPtr password,
             LogonFlags logonFlags,
-            [MarshalAs(UnmanagedType.LPTStr)] string appName,
+            string appName,
             StringBuilder cmdLine,
             int creationFlags,
             IntPtr environmentBlock,
-            [MarshalAs(UnmanagedType.LPTStr)] string lpCurrentDirectory,
+            string lpCurrentDirectory,
             Interop.Kernel32.STARTUPINFO lpStartupInfo,
-            Interop.Kernel32.PROCESS_INFORMATION lpProcessInformation);
+            [Out] Interop.Kernel32.PROCESS_INFORMATION lpProcessInformation);
 
         [Flags]
         internal enum LogonFlags

src/Common/src/Interop/Windows/kernel32/Interop.CreateProcess.cs

@@ -13,20 +13,20 @@ internal partial class Kernel32
     {
         [DllImport(Libraries.Kernel32, CharSet = CharSet.Unicode, SetLastError = true, BestFitMapping = false, EntryPoint = "CreateProcessW")]
         internal static extern bool CreateProcess(
-            [MarshalAs(UnmanagedType.LPTStr)] string lpApplicationName,
+            string lpApplicationName,
             StringBuilder lpCommandLine,
             ref SECURITY_ATTRIBUTES procSecAttrs,
             ref SECURITY_ATTRIBUTES threadSecAttrs,
             bool bInheritHandles,
             int dwCreationFlags,
             IntPtr lpEnvironment,
-            [MarshalAs(UnmanagedType.LPTStr)] string lpCurrentDirectory,
+            string lpCurrentDirectory,
             STARTUPINFO lpStartupInfo,
             [Out] PROCESS_INFORMATION lpProcessInformation
         );
 
         [StructLayout(LayoutKind.Sequential)]
-        internal class PROCESS_INFORMATION
+        internal sealed class PROCESS_INFORMATION
         {
             internal IntPtr hProcess = IntPtr.Zero;
             internal IntPtr hThread = IntPtr.Zero;
@@ -35,7 +35,7 @@ internal class PROCESS_INFORMATION
         }
 
         [StructLayout(LayoutKind.Sequential)]
-        internal class STARTUPINFO : IDisposable
+        internal sealed class STARTUPINFO : IDisposable
         {
             internal int cb;
             internal IntPtr lpReserved = IntPtr.Zero;
@@ -59,7 +59,7 @@ internal class STARTUPINFO : IDisposable
             internal
                 STARTUPINFO()
             {
-                cb = Marshal.SizeOf(this);
+                cb = Marshal.SizeOf<STARTUPINFO>();
             }
 
             public void Dispose()

src/System.Diagnostics.Process/src/System/Diagnostics/ProcessManager.Windows.cs

@@ -758,7 +758,7 @@ private static unsafe ProcessInfo[] GetProcessInfos(IntPtr dataPtr, Predicate<in
                     // get the threads for current process
                     processInfos[processInfo.ProcessId] = processInfo;
 
-                    currentPtr = (IntPtr)((long)currentPtr + Marshal.SizeOf(pi));
+                    currentPtr = (IntPtr)((long)currentPtr + sizeof(SystemProcessInformation));
                     int i = 0;
                     while (i < pi.NumberOfThreads)
                     {
@@ -774,7 +774,7 @@ private static unsafe ProcessInfo[] GetProcessInfos(IntPtr dataPtr, Predicate<in
                         threadInfo._threadWaitReason = NtProcessManager.GetThreadWaitReason((int)ti.WaitReason);
 
                         processInfo._threadInfoList.Add(threadInfo);
-                        currentPtr = (IntPtr)((long)currentPtr + Marshal.SizeOf(ti));
+                        currentPtr = (IntPtr)((long)currentPtr + sizeof(SystemThreadInformation));
                         i++;
                     }
                 }