Use raw_pwrite_stream in the object writer/streamer.

The ELF object writer will take advantage of that in the next commit.

llvm-svn: 234950
diff --git a/llvm/lib/Target/TargetMachineC.cpp b/llvm/lib/Target/TargetMachineC.cpp
index afba80f..1a5bf16 100644
--- a/llvm/lib/Target/TargetMachineC.cpp
+++ b/llvm/lib/Target/TargetMachineC.cpp
@@ -183,7 +183,7 @@
 }
 
 static LLVMBool LLVMTargetMachineEmit(LLVMTargetMachineRef T, LLVMModuleRef M,
-                                      raw_ostream &OS,
+                                      raw_pwrite_stream &OS,
                                       LLVMCodeGenFileType codegen,
                                       char **ErrorMessage) {
   TargetMachine* TM = unwrap(T);