Fix a CrossGen CreatePDB issue that caused a Windows build break

CrossGen /CreatePDB command gives preference to the TPA list while loading assemblies. So if the TPA contains the IL version of the input assembly but not the NI version, we would end up loading the IL instead of NI. This causes the CreatePDB command to fail, since it can't operate on IL images. This is fixed by putting the input file as the first entry in the TPA list.

Another issue is when the above error does occur, the error message is very unclear (it only shows "Unspecified error"). This is fixed with a better error message.

[tfs-changeset: 1587876]

Author: John Chen

src/tools/crossgen/crossgen.cpp

@@ -850,6 +850,14 @@ int _cdecl wmain(int argc, __in_ecount(argc) WCHAR **argv)
 
 #ifdef FEATURE_CORECLR
     SString ssTPAList;  
+
+    if (fCreatePDB)
+    {
+        // While creating PDB, assembly binder gives preference to files in TPA.
+        // This can create difficulties if the input file is not in TPA.
+        // To avoid this issue, put the input file as the first item in TPA.
+        ssTPAList.Append(pwzFilename);
+    }
 
     // Are we compiling mscorlib.dll? 
     bool fCompilingMscorlib = StringEndsWith((LPWSTR)pwzFilename, W("mscorlib.dll"));

src/vm/compile.cpp

@@ -4812,8 +4812,10 @@ HRESULT __stdcall CreatePdb(CORINFO_ASSEMBLY_HANDLE hAssembly, BSTR pNativeImage
     if (!fAtLeastOneNativeModuleFound)
     {
         GetSvcLogger()->Printf(
+            W("Loaded image '%s' (for input file '%s') is not a native image.\n"),
+            pAssembly->GetManifestFile()->GetPath().GetUnicode(),
             pNativeImagePath);
-        return E_FAIL;
+        return CORDBG_E_NO_IMAGE_AVAILABLE;
     }
 
     GetSvcLogger()->Printf(