Subzero. ARM32. No more SP frobbing.

Pre-computes the max stack size outgoing arguments, and pre-allocates
it during prolog, deallocating during epilog.

With this CL, there are no more StackAdjustments needed for the ARM32,
which will simplify rematerializing alloca'd variables.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4076
R=sehr@chromium.org

Review URL: https://codereview.chromium.org/1467473003 .

src/IceTargetLoweringMIPS32.h

diff --git a/src/IceTargetLoweringMIPS32.h b/src/IceTargetLoweringMIPS32.h
index 5523360..387ec2e 100644
--- a/src/IceTargetLoweringMIPS32.h
+++ b/src/IceTargetLoweringMIPS32.h
@@ -235,6 +235,10 @@
   void lowerSwitch(const InstSwitch *Inst) override;
   void lowerUnreachable(const InstUnreachable *Inst) override;
   void prelowerPhis() override;
+  uint32_t getCallStackArgumentsSizeBytes(const InstCall *Instr) override {
+    (void)Instr;
+    return 0;
+  }
   void genTargetHelperCallFor(Inst *Instr) override { (void)Instr; }
   void doAddressOptLoad() override;
   void doAddressOptStore() override;