This fixes the following failure:
C:\[...]\llvm\tools\clang\test\VFS\external-names.c:34:26: error: CHECK-DEBUG-EXTERNAL: expected string not found in input // CHECK-DEBUG-EXTERNAL: ![[Num]] = !DIFile(filename: "{{[^"]*}}Inputs{{.}}external-names.h" ^ [...] <stdin>:42:54: note: possible intended match here !10 = !DIFile(filename: "C:/[...]\\llvm\\tools\\clang\\test\\VFS\\Inputs\\external-names.h", directory: "")