Move virtual camera service (build flag)

from base_system.mk to handheld_system.mk.
Virtual camera service doesn't make sense on devices
without camera server (which is defined in handheld_system.mk).

Bug: 301023410
Bug: 311679099
Test: build
Ignore-AOSP-First: Virtual Camera HAL target is not merged in AOSP.
Change-Id: I67c18cfa7a2717cce738b17a53199fa595254068
diff --git a/target/product/handheld_system.mk b/target/product/handheld_system.mk
index d5c2a87..309ef0c 100644
--- a/target/product/handheld_system.mk
+++ b/target/product/handheld_system.mk
@@ -75,6 +75,7 @@
     VpnDialogs \
     vr \
 
+PRODUCT_PACKAGES += $(RELEASE_PACKAGE_VIRTUAL_CAMERA)
 
 PRODUCT_SYSTEM_SERVER_APPS += \
     FusedLocation \