Subzero: Add -Wshadow to the build.

src/IceELFObjectWriter.cpp

Index: src/IceELFObjectWriter.cpp
diff --git a/src/IceELFObjectWriter.cpp b/src/IceELFObjectWriter.cpp
index eca340312a101edb9275a054a2b2d915d1e0c9f4..1a8d335ef14087cd680396143b081f0eb4deb9cc 100644
--- a/src/IceELFObjectWriter.cpp
+++ b/src/IceELFObjectWriter.cpp
@@ -20,7 +20,12 @@
 #include "IceGlobalContext.h"
 #include "IceGlobalInits.h"
 #include "IceOperand.h"
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-parameter"
+#pragma clang diagnostic ignored "-Wshadow"
 #include "llvm/Support/MathExtras.h"
+#pragma clang diagnostic pop
 
 using namespace llvm::ELF;
 
@@ -63,8 +68,8 @@ uint32_t getELFFlags(TargetArch Arch) {
 
 } // end of anonymous namespace
 
-ELFObjectWriter::ELFObjectWriter(GlobalContext &Ctx, ELFStreamer &Out)
-    : Ctx(Ctx), Str(Out), ELF64(isELF64(Ctx.getFlags().getTargetArch())) {
+ELFObjectWriter::ELFObjectWriter(GlobalContext &MyCtx, ELFStreamer &Out)
+    : Ctx(MyCtx), Str(Out), ELF64(isELF64(Ctx.getFlags().getTargetArch())) {
   // Create the special bookkeeping sections now.
   const IceString NullSectionName("");
   NullSection = new (Ctx.allocate<ELFSection>())
@@ -316,7 +321,6 @@ void ELFObjectWriter::writeDataOfType(SectionType ST,
     return;
   ELFDataSection *Section;
   ELFRelocationSection *RelSection;
-  IceString SectionName;
   Elf64_Xword ShAddralign = 1;
   for (VariableDeclaration *Var : Vars) {
     Elf64_Xword Align = Var->getAlignment();