Only test bridge object pre-specialization on Darwin

Bridge objects don't exist on other platforms

Author: drexin

test/SILOptimizer/pre_specialize_layouts.swift

@@ -88,9 +88,9 @@ internal func testEmitIntoClient<T>(t: T) {
 // OPT: apply [[F7]]([[A2]]) : $@convention(thin) (@guaranteed AnyObject) -> ()
 // OPT: [[A3:%.*]] = alloc_stack $OveralignedReferenceWrapperStruct
 // OPT: apply {{%.*}}<OveralignedReferenceWrapperStruct>([[A3]])
-// OPT: [[F8:%.*]] = function_ref @$s30pre_specialized_module_layouts20publicPrespecializedyyxlFBb_Ts5 : $@convention(thin) (@guaranteed Builtin.BridgeObject) -> ()
-// OPT: [[A4:%.*]] = unchecked_bitwise_cast [[P3]] : $Array<Int> to $Builtin.BridgeObject
-// OPT: apply [[F8]]([[A4]]) : $@convention(thin) (@guaranteed Builtin.BridgeObject) -> ()
+// OPT-macosx: [[F8:%.*]] = function_ref @$s30pre_specialized_module_layouts20publicPrespecializedyyxlFBb_Ts5 : $@convention(thin) (@guaranteed Builtin.BridgeObject) -> ()
+// OPT-macosx: [[A4:%.*]] = unchecked_bitwise_cast [[P3]] : $Array<Int> to $Builtin.BridgeObject
+// OPT-macosx: apply [[F8]]([[A4]]) : $@convention(thin) (@guaranteed Builtin.BridgeObject) -> ()
 // OPT:   [[F3:%.*]] = function_ref @$s30pre_specialized_module_layouts36internalEmitIntoClientPrespecializedyyxlFSi_Ts5 : $@convention(thin) (Int) -> ()
 // OPT:   apply [[F3]]
 // OPT:   [[F4:%.*]] = function_ref @$s30pre_specialized_module_layouts36internalEmitIntoClientPrespecializedyyxlFSd_Ts5 : $@convention(thin) (Double) -> ()