[turbofan] Add support for overflow add/sub to the MachineOperatorReducer.

include/v8config.h

Index: include/v8config.h
diff --git a/include/v8config.h b/include/v8config.h
index a7ef63d88b7ff3acc57b8119fc047402c5dbfae0..87de99417067f6222dd80b1712bb01cd6e586342 100644
--- a/include/v8config.h
+++ b/include/v8config.h
@@ -179,6 +179,8 @@
 //  V8_HAS_BUILTIN_CTZ                  - __builtin_ctz() supported
 //  V8_HAS_BUILTIN_EXPECT               - __builtin_expect() supported
 //  V8_HAS_BUILTIN_POPCOUNT             - __builtin_popcount() supported
+//  V8_HAS_BUILTIN_SADD_OVERFLOW        - __builtin_sadd_overflow() supported
+//  V8_HAS_BUILTIN_SSUB_OVERFLOW        - __builtin_ssub_overflow() supported
 //  V8_HAS_DECLSPEC_ALIGN               - __declspec(align(n)) supported
 //  V8_HAS_DECLSPEC_DEPRECATED          - __declspec(deprecated) supported
 //  V8_HAS_DECLSPEC_NOINLINE            - __declspec(noinline) supported
@@ -213,6 +215,8 @@
 # define V8_HAS_BUILTIN_CTZ (__has_builtin(__builtin_ctz))
 # define V8_HAS_BUILTIN_EXPECT (__has_builtin(__builtin_expect))
 # define V8_HAS_BUILTIN_POPCOUNT (__has_builtin(__builtin_popcount))
+# define V8_HAS_BUILTIN_SADD_OVERFLOW (__has_builtin(__builtin_sadd_overflow))
+# define V8_HAS_BUILTIN_SSUB_OVERFLOW (__has_builtin(__builtin_ssub_overflow))
 
 # define V8_HAS_CXX11_ALIGNAS (__has_feature(cxx_alignas))
 # define V8_HAS_CXX11_STATIC_ASSERT (__has_feature(cxx_static_assert))