[NFC] Mark cross-import overlay + module trace test unsupported on Windows. (#29977)

Author: varungandhi-apple

test/CrossImport/module-trace.swift

@@ -1,5 +1,8 @@
 // This file tests that we emit cross-imports into module interfaces.
 
+// FIXME: Fix the path normalization issue and get rid of this.
+// UNSUPPORTED: OS=windows-msvc
+
 // RUN: %empty-directory(%t)
 // RUN: cp -r %S/Inputs/lib-templates/* %t/