test/DebugInfo/dwarfdump-test.test: Tweak expressions for Win32 to match...

test/DebugInfo/dwarfdump-test.test: Tweak expressions for Win32 to match backslashes. They are still odd, though.

For example, Paths are printed on Win32 as below;

/tmp/dbginfo\def2.cc:4:0
/tmp/dbginfo\include\decl2.h:1:0
/tmp/include\decl.h:5:0

llvm-svn: 160505