cmGlobalGenerator: FindMakeProgram() before CMakeDetermineSystem

Prior to 147d36c, the build tool was found before the toolset was
selected, but was changed to be found after in order to support a
64-bit MSBuild (introduced in da402a0.) However, a bug was found in
64-bit MSBuild, which resulted in da402a0 being reverted in
f3cedf3 (but 147d36c was not reverted.) Move FindMakeProgram() even
earlier than it was before 147d36c, before CMakeDetermineSystem is
called, so that the Visual Studio Android support can report its
sysroot, giving Android-Determine the information it needs to
inspect the NDK.

When the bug in 64-bit MSBuild is fixed, we will have a chicken-and-
egg problem, but we don't need to worry about it for now.

Source/cmGlobalGenerator.cxx

@@ -596,6 +596,16 @@ void cmGlobalGenerator::EnableLanguage(
       mf->ReadListFile(fpath);
     }
   }
+
+  if (readCMakeSystem) {
+    // Find the native build tool for this generator.
+    // This has to be done early so that MSBuild can be used to examine the
+    // cross-compilation environment.
+    if (!this->FindMakeProgram(mf)) {
+      return;
+    }
+  }
+
   //  Load the CMakeDetermineSystem.cmake file and find out
   // what platform we are running on
   if (!mf->GetDefinition("CMAKE_SYSTEM")) {
@@ -667,11 +677,6 @@ void cmGlobalGenerator::EnableLanguage(
       cmSystemTools::SetFatalErrorOccured();
       return;
     }
-
-    // Find the native build tool for this generator.
-    if (!this->FindMakeProgram(mf)) {
-      return;
-    }
   }
 
   // Check that the languages are supported by the generator and its