build: avoid underlinking FirebaseCore on Android

There is an undefined reference to liblog symbols when building for
Android. Ensure that we are fulfilling all the requirements when linking
the DSO.

CMakeLists.txt

@@ -60,6 +60,7 @@ target_link_libraries(FirebaseCore PUBLIC
 target_link_libraries(FirebaseCore PRIVATE
   firebase_app
   flatbuffers
+  $<$<PLATFORM_ID:ANDROID>:log>
   $<$<PLATFORM_ID:Windows>:libcurl>
   $<$<PLATFORM_ID:Windows>:zlibstatic>)
 if(ANDROID)