[gn] port 0c7c82a

Author: nico

llvm/utils/gn/secondary/llvm/test/BUILD.gn

@@ -64,6 +64,7 @@ write_lit_config("lit_site_cfg") {
     "LLVM_APPEND_VC_REV=0",
     "LLVM_ENABLE_FFI=0",
     "LLVM_ENABLE_HTTPLIB=0",
+    "LLVM_EXPERIMENTAL_KEY_INSTRUCTIONS=0",
     "LLVM_FORCE_VC_REVISION=",
     "LLVM_HAS_LOGF128=0",
     "LLVM_HAVE_OPT_VIEWER_MODULES=0",