Fix no-inline compiler flag on Windows

-fno-inline is unavailable on clang-cl nor cl.exe, and causes a build
failure on Windows bot.
This CL updates that flag to "/Ob0", which is msvc-equivalent of
-fno-inline.

Change-Id: Id9ffed03a855ac0b773ee28625472de664c3cb30
Reviewed-on: https://chromium-review.googlesource.com/c/1442013
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59185}

BUILD.gn

@@ -593,11 +593,15 @@ config("toolchain") {
   }
 
   if (v8_no_inline) {
+    if (is_win) {
+      cflags += [ "/Ob0" ]
+    } else {
       cflags += [
         "-fno-inline-functions",
         "-fno-inline",
       ]
     }
+  }
 
   if (is_clang) {
     cflags += [