Propagate InstructionSetFeatures to ElfBuilder.

This is subset of CL171665 and it separates it into two.
It will be needed to generate .MIPS.abiflags ELF section.

Change-Id: I5557e7cb98d0fa1dc57c85cf6161e119c6d50a1a
diff --git a/compiler/oat_test.cc b/compiler/oat_test.cc
index 14fd105..d22044a 100644
--- a/compiler/oat_test.cc
+++ b/compiler/oat_test.cc
@@ -176,6 +176,7 @@
                   bool verify) {
     std::unique_ptr<ElfWriter> elf_writer = CreateElfWriterQuick(
         compiler_driver_->GetInstructionSet(),
+        compiler_driver_->GetInstructionSetFeatures(),
         &compiler_driver_->GetCompilerOptions(),
         file);
     elf_writer->Start();