gralloc: change heap id for secure buffers on Guest VM

For hypervisor build, allocate secure buffer from carved-out
pool, instead of system heap.

Change-Id: I5f1638867c03fc2528bf80000352d6b7ddffc471
diff --git a/gralloc/Android.mk b/gralloc/Android.mk
index 9ad44e5..ee37c1f 100644
--- a/gralloc/Android.mk
+++ b/gralloc/Android.mk
@@ -49,6 +49,9 @@
 LOCAL_SHARED_LIBRARIES        := $(common_libs) libqdMetaData libdl libgrallocutils libion \
                                   android.hardware.graphics.mapper@2.1
 LOCAL_CFLAGS                  := $(common_flags) -DLOG_TAG=\"qdgralloc\" -Wno-sign-conversion
+ifeq ($(ENABLE_HYP),true)
+LOCAL_CFLAGS += -DHYPERVISOR
+endif
 LOCAL_ADDITIONAL_DEPENDENCIES := $(common_deps)
 LOCAL_SRC_FILES               := gr_allocator.cpp gr_buf_mgr.cpp gr_ion_alloc.cpp
 include $(BUILD_SHARED_LIBRARY)