deps: define V8_PRESERVE_MOST as no-op on Windows

It's causing linker errors with node.lib in node-gyp and potentially
breaks other 3rd party tools

common.gypi

@@ -36,7 +36,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.11',
+    'v8_embedder_string': '-node.12',
 
     ##### V8 defaults for Node.js #####
 

deps/v8/include/v8config.h

@@ -581,11 +581,15 @@ path. Add it with -I<path> to the command line
 // functions.
 // Use like:
 //   V8_NOINLINE V8_PRESERVE_MOST void UnlikelyMethod();
+#if V8_OS_WIN
+# define V8_PRESERVE_MOST
+#else
 #if V8_HAS_ATTRIBUTE_PRESERVE_MOST
 # define V8_PRESERVE_MOST __attribute__((preserve_most))
 #else
 # define V8_PRESERVE_MOST /* NOT SUPPORTED */
 #endif
+#endif
 
 
 // A macro (V8_DEPRECATED) to mark classes or functions as deprecated.