Remove deprecated WITH_HOST_DALVIK.

Bug: 13751317
Fix the Mac host build:
 - conditionally define constants using pre-existing pattern,
 - make Posix calls that the Mac doesn't support throw
   UnsupportedOperationException.

Change-Id: Ib68887cbe36ab167d042eb96c7834bce0651b078
diff --git a/CaCerts.mk b/CaCerts.mk
index 980d0fb..f85f524 100644
--- a/CaCerts.mk
+++ b/CaCerts.mk
@@ -50,10 +50,9 @@
 # This is so that build/target/product/core.mk can use cacerts in PRODUCT_PACKAGES
 ALL_MODULES.cacerts.INSTALLED := $(cacerts_target)
 
-ifeq ($(WITH_HOST_DALVIK),true)
 cacerts_host_directory := $(HOST_OUT)/etc/security/cacerts
 $(foreach cacert, $(cacerts), $(eval $(call include-prebuilt-with-destination-directory,host-cacert-$(notdir $(cacert)),$(cacert),$(cacerts_host_directory))))
-endif
+
 cacerts_host := $(addprefix $(cacerts_host_directory)/,$(foreach cacert,$(cacerts),$(notdir $(cacert))))
 .PHONY: cacerts-host
 cacerts-host: $(cacerts_host)