Floating point callee save support in exception delivery.

Untested until we promote floating point values in the compiler.

Change-Id: I20fe66cb59e2f31b21043479dde898326aec668f
diff --git a/src/context_arm.h b/src/context_arm.h
index e5a5118..31a1a2a 100644
--- a/src/context_arm.h
+++ b/src/context_arm.h
@@ -28,7 +28,7 @@
 
  private:
   uintptr_t gprs_[16];
-  float fprs_[32];
+  uint32_t fprs_[32];
 };
 
 }  // namespace arm