Provide a host etc directory

This allows host etc modules to be installed in out/host/*. One use case
for this is art cc tests which have some data dependencies.

Test: presubmits
Change-Id: I2f0168f68c17c2fa4999d3cfcde7845eaef0bd48
diff --git a/core/envsetup.mk b/core/envsetup.mk
index c063f60..f82e861 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -417,6 +417,7 @@
 HOST_OUT_NATIVE_TESTS := $(HOST_OUT)/nativetest64
 HOST_OUT_COVERAGE := $(HOST_OUT)/coverage
 HOST_OUT_TESTCASES := $(HOST_OUT)/testcases
+HOST_OUT_ETC := $(HOST_OUT)/etc
 .KATI_READONLY := \
   HOST_OUT_EXECUTABLES \
   HOST_OUT_SHARED_LIBRARIES \
@@ -425,7 +426,8 @@
   HOST_OUT_SDK_ADDON \
   HOST_OUT_NATIVE_TESTS \
   HOST_OUT_COVERAGE \
-  HOST_OUT_TESTCASES
+  HOST_OUT_TESTCASES \
+  HOST_OUT_ETC
 
 HOST_CROSS_OUT_EXECUTABLES := $(HOST_CROSS_OUT)/bin
 HOST_CROSS_OUT_SHARED_LIBRARIES := $(HOST_CROSS_OUT)/lib