[WIP] Produce SVG stderr output for Windows

Need to update tests from CI failure.

Author: estebank

src/tools/compiletest/src/runtest.rs

@@ -4014,12 +4014,17 @@ impl<'test> TestCx<'test> {
         explicit_format: bool,
     ) -> usize {
         let stderr_bits = format!("{}bit.stderr", self.config.get_pointer_width());
-        let force_color_svg = self.props.compile_flags.iter().any(|s| s.contains("--color"))
-            && !self.config.target.contains("windows");
+        let force_color_svg = self.props.compile_flags.iter().any(|s| s.contains("--color"));
         let (stderr_kind, stdout_kind) = match output_kind {
             TestOutput::Compile => (
                 if force_color_svg {
-                    UI_SVG
+                    if self.config.target.contains("windows") {
+                        // We single out Windows here because some of the CLI coloring is
+                        // specifically changed for Windows.
+                        "windows.svg"
+                    } else {
+                        UI_SVG
+                    }
                 } else if self.props.stderr_per_bitwidth {
                     &stderr_bits
                 } else {