8000461: Top level build doesn't pass OPENJDK=true through to the hotspot build

Summary: Add OPENJDK to the COMMON_BUILD_ARGUMENTS
Reviewed-by: tbell

make/Defs-internal.gmk

@@ -330,6 +330,10 @@ COMMON_BUILD_ARGUMENTS = \
     PREVIOUS_MINOR_VERSION=$(PREVIOUS_MINOR_VERSION) \
     PREVIOUS_MICRO_VERSION=$(PREVIOUS_MICRO_VERSION)
 
+ifdef OPENJDK
+  COMMON_BUILD_ARGUMENTS += OPENJDK=$(OPENJDK)
+endif
+
 ifdef ARCH_DATA_MODEL
   COMMON_BUILD_ARGUMENTS += ARCH_DATA_MODEL=$(ARCH_DATA_MODEL)
 endif