[DevTools] Fix V8 inspector compilation on SmartOS

SmartOS does not have snprintf in std namespace (even though it has the
headers). This change imports global symbol into std namespace.

R=dgozman@chromium.org, pfeldman@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2262403002
Cr-Original-Commit-Position: refs/heads/master@{#413629}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 202452fc4e5633afadb5ef5193efc20bbc3cc22f
diff --git a/PlatformSTL.h b/PlatformSTL.h
index dd1fb45..bfba971 100644
--- a/PlatformSTL.h
+++ b/PlatformSTL.h
@@ -308,4 +308,10 @@
 } // namespace std
 #endif // (_WIN32) && defined( _MSC_VER ) && (_MSC_VER < 1900)
 
+#ifdef __sun
+namespace std {
+using ::snprintf;
+} // namespace std
+#endif // __sun
+
 #endif // PlatformSTL_h