[test] Mark archive-as-start-lib.s as unsupported on Windows

gnuwin32 tail does not support the `tail -c +9` syntax.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D119956

lld/test/ELF/archive-as-start-lib.s

@@ -1,4 +1,5 @@
 # REQUIRES: x86
+# UNSUPPORTED: system-windows
 
 # RUN: rm -rf %t && split-file %s %t && cd %t
 # RUN: llvm-mc -filetype=obj -triple=x86_64 a.s -o a.o