[BUILD] Check for inconsistent build configuration

This makes sure that BUILDING_V8_SHARED and USING_V8_SHARED are not
both set at once.

Change-Id: Iba3a4fac37518b6ec3658da4575453a7967ece0f
Bug: v8:8855
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627978Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62369}

include/v8config.h

@@ -353,6 +353,12 @@
 #define V8_WARN_UNUSED_RESULT /* NOT SUPPORTED */
 #endif
 
+#if defined(BUILDING_V8_SHARED) && defined(USING_V8_SHARED)
+#error Inconsistent build configuration: To build the V8 shared library \
+set BUILDING_V8_SHARED, to include its headers for linking against the \
+V8 shared library set USING_V8_SHARED.
+#endif
+
 #ifdef V8_OS_WIN
 
 // Setup for Windows DLL export/import. When building the V8 DLL the