List Subzero's local optlevel flags after LLVM's cxxflags (precedence).

Ended up needing to fix the InstX8632Lockable error that JF ran into
now that -O0 is really -O0:
https://codereview.chromium.org/512933006/

BUG=none
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/557933002
diff --git a/Makefile.standalone b/Makefile.standalone
index bac279a..095e8f1 100644
--- a/Makefile.standalone
+++ b/Makefile.standalone
@@ -41,8 +41,8 @@
 OPTLEVEL := -O0
 CXX := g++
 
-CXXFLAGS := -Wall -Wextra -Werror -fno-rtti -fno-exceptions \
-	$(OPTLEVEL) -g $(LLVM_CXXFLAGS) $(HOST_FLAGS) \
+CXXFLAGS := $(LLVM_CXXFLAGS) -Wall -Wextra -Werror -fno-rtti \
+	-fno-exceptions $(OPTLEVEL) -g $(HOST_FLAGS) \
 	-Wno-error=unused-parameter
 LDFLAGS := $(HOST_FLAGS)
 
diff --git a/src/IceInstX8632.h b/src/IceInstX8632.h
index 04902d2..918b774 100644
--- a/src/IceInstX8632.h
+++ b/src/IceInstX8632.h
@@ -674,10 +674,6 @@
 
 // Base class for a lockable x86-32 instruction (emits a locked prefix).
 class InstX8632Lockable : public InstX8632 {
-public:
-  virtual void emit(const Cfg *Func) const = 0;
-  virtual void dump(const Cfg *Func) const;
-
 protected:
   bool Locked;