test: support / and \ as directory separators

Windows uses \ as the directory separator and this causes the tests to fail on
Windows.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@273036 91177308-0d34-0410-b5e6-96231b3b80d8

test/Driver/windows-cross.c

@@ -69,8 +69,8 @@
 
 // RUN: %clang -### -target armv7-windows-itanium -isystem-after "Windows Kits/10/Include/10.0.10586.0/ucrt" -isystem-after "Windows Kits/10/Include/10.0.10586.0/um" -isystem-after "Windows Kits/10/Include/10.0.10586.0/shared" -c %s -o /dev/null 2>&1 \
 // RUN:     | FileCheck %s --check-prefix CHECK-ISYSTEM-AFTER
-// CHECK-ISYSTEM-AFTER: "-internal-isystem" "{{.*}}/clang/{{[\.0-9]+}}/include"
-// CHECK-ISYSTEM-AFTER: "-internal-isystem" "Windows Kits/10/Include/10.0.10586.0/ucrt"
-// CHECK-ISYSTEM-AFTER: "-internal-isystem" "Windows Kits/10/Include/10.0.10586.0/um"
-// CHECK-ISYSTEM-AFTER: "-internal-isystem" "Windows Kits/10/Include/10.0.10586.0/shared"
+// CHECK-ISYSTEM-AFTER: "-internal-isystem" "{{.*}}{{[/\\]}}clang{{[/\\]}}{{[\.0-9]+}}{{[/\\]}}include"
+// CHECK-ISYSTEM-AFTER: "-internal-isystem" "Windows Kits{{[/\\]}}10{{[/\\]}}Include{{[/\\]}}10.0.10586.0{{[/\\]}}ucrt"
+// CHECK-ISYSTEM-AFTER: "-internal-isystem" "Windows Kits{{[/\\]}}10{{[/\\]}}Include{{[/\\]}}10.0.10586.0{{[/\\]}}um"
+// CHECK-ISYSTEM-AFTER: "-internal-isystem" "Windows Kits{{[/\\]}}10{{[/\\]}}Include{{[/\\]}}10.0.10586.0{{[/\\]}}shared"