Don't duplicate OS::CpuFeaturesImpliedByPlatform for every POSIX platform.

src/platform-solaris.cc

Index: src/platform-solaris.cc
diff --git a/src/platform-solaris.cc b/src/platform-solaris.cc
index cb9ba18f97289044f5ea5d15fa531b9735e01e93..46fff60e191466e72d0cb6e899556841ef58bf01 100644
--- a/src/platform-solaris.cc
+++ b/src/platform-solaris.cc
@@ -84,11 +84,6 @@ namespace internal {
 static Mutex* limit_mutex = NULL;
 
 
-uint64_t OS::CpuFeaturesImpliedByPlatform() {
-  return 0;  // Solaris runs on a lot of things.
-}
-
-
 int OS::ActivationFrameAlignment() {
   // GCC generates code that requires 16 byte alignment such as movdqa.
   return Max(STACK_ALIGN, 16);