[build] Fix V8_VERSION_STRING with embedder string

Fixes the value of V8_VERSION_STRING to add the embedder string when the
patch level is zero.

BUG=v8:5740

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Idfe2020fe857865ff75a91ddb57f18ed23dfe3a7
Reviewed-on: https://chromium-review.googlesource.com/732992
Commit-Queue: Franziska Hinkelmann <franzih@chromium.org>
Reviewed-by: Franziska Hinkelmann <franzih@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48834}

include/v8-version-string.h

@@ -29,9 +29,10 @@
   "." V8_S(V8_MINOR_VERSION) "." V8_S(V8_BUILD_NUMBER) "." V8_S( \
       V8_PATCH_LEVEL) V8_EMBEDDER_STRING V8_CANDIDATE_STRING
 #else
-#define V8_VERSION_STRING \
-  V8_S(V8_MAJOR_VERSION)  \
-  "." V8_S(V8_MINOR_VERSION) "." V8_S(V8_BUILD_NUMBER) V8_CANDIDATE_STRING
+#define V8_VERSION_STRING                              \
+  V8_S(V8_MAJOR_VERSION)                               \
+  "." V8_S(V8_MINOR_VERSION) "." V8_S(V8_BUILD_NUMBER) \
+      V8_EMBEDDER_STRING V8_CANDIDATE_STRING
 #endif
 
 #endif  // V8_VERSION_STRING_H_