[COFF] Add missing Requires x86 to fix buildbot
[COFF] Add missing Requires x86 to fix buildbot

Add REQUIRES: x86 to pdb-debug-f.s as this is causing the Arm and
AArch64 buildbots to fail as they do not have the x86 backend.

Differential Revision: https://reviews.llvm.org/D52606



git-svn-id: f6089bf0e6284f307027cef4f64114ee9ebb0424@343196 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/lld,llvm-mirror/lld