[gn] Add target flags to asmflags.

Reviewers: pcc, thakis

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D58483

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354618 91177308-0d34-0410-b5e6-96231b3b80d8

utils/gn/build/BUILD.gn

@@ -10,6 +10,7 @@ config("compiler_defaults") {
     defines += [ "NDEBUG" ]
   }
 
+  asmflags = target_flags
   cflags = target_flags
   ldflags = target_flags + target_ldflags