[LIT] Fix system-windows

Turns out if you were on windows and your default target wasn't windows the system-windows feature wasn't getting enabled.

This fixes that and updates the coff-dwarf test to rely on the new "target-windows" feature. That test was the reason why system-windows was changed to not always be enabled on Windows hosts.

llvm-svn: 289503

llvm/test/tools/llvm-config/system-libs.test

 RUN: llvm-config --system-libs 2>&1 | FileCheck %s
-UNSUPPORTED: win32
+UNSUPPORTED: system-windows
 CHECK: -l
 CHECK-NOT: error
 CHECK-NOT: warning

llvm/test/tools/llvm-symbolizer/coff-dwarf.test

@@ -3,7 +3,7 @@ RUN:     | llvm-symbolizer --inlining --relative-address -obj="%p/Inputs/coff-dw
 RUN:     | FileCheck %s
 
 This test relies on UnDecorateSymbolName, which is Windows-only.
-REQUIRES: system-windows
+REQUIRES: target-windows
 
 ADDR: 0x5009
 ADDR: 0x5038