[NVPTX] Fix NVPTX DebugInfo tests on Windows

[asavonic]

Summary

These tests were added in D121299 and they failed on Windows:

    error: CHECK-NODIR: expected string
    not found in input
    ; CHECK-NODIR: .file {{[0-9]+}} "/tmp/dbginfo/a/a.cpp"
		   ^
    <stdin>:1:1: note: scanning from here
    //
    ^
    <stdin>:25:2: note: possible intended match here
     .file 1 "/tmp/dbginfo/a\\a.cpp"

I don't have a windows machine to test this, but I've seen this {{/|\\\\}}
pattern in other NVPTX tests, so I hope it works.

[asavonic]

I missed two other tests that failed because of the same issue: debug-file-loc.ll and debug-file-loc-only.ll.
@thakis tried to fix them in a1bb5719eca6 (thanks a lot!), but I'm not sure if it helped - we need two backslash characters in the regex.

[thakis]

LG, thanks!

[asavonic]

Merged 99333026607f.

llvm/test/DebugInfo/NVPTX/dwarf-file-dir.ll

 ; RUN: llc < %s -mtriple=nvptx64-nvidia-cuda | FileCheck --check-prefix=CHECK-NODIR %s
 ; RUN: llc < %s -mtriple=nvptx64-nvidia-cuda -dwarf-directory=1 | FileCheck --check-prefix=CHECK-DIR %s
 
-; compilation on Windows results in: /tmp/dbginfo/a\\a.cpp
-; UNSUPPORTED: windows
-
-; CHECK-NODIR: .file   {{[0-9]+}} "/tmp/dbginfo/a/a.cpp"
+; CHECK-NODIR: .file   {{[0-9]+}} "/tmp/dbginfo/a{{/|\\\\}}a.cpp"
 ;
 ; ptxas does not support .file directory syntax, but it can still be
 ; forced by -dwarf-directory=1
 ; CHECK-DIR:   .file   {{[0-9]+}} "/tmp/dbginfo/a" "a.cpp"
 
 define void @_Z4funcv() !dbg !4 {
 entry:
   ret void, !dbg !5