[optimizing compiler] Add CMP{L,G}_{FLOAT,DOUBLE}

- adds float comparison for arm, x86, x86_64 backends.
- adds ucomis{s,d} assembly to x86 and x86_64.

Change-Id: I232d2b6e9ecf373beb5cc63698dd97a658ff9c83
diff --git a/compiler/utils/x86/constants_x86.h b/compiler/utils/x86/constants_x86.h
index 45c3834..2dfb65c 100644
--- a/compiler/utils/x86/constants_x86.h
+++ b/compiler/utils/x86/constants_x86.h
@@ -96,7 +96,8 @@
   kZero         = kEqual,
   kNotZero      = kNotEqual,
   kNegative     = kSign,
-  kPositive     = kNotSign
+  kPositive     = kNotSign,
+  kUnordered    = kParityEven
 };