trusty: Add host build for rpmb_dev

Building rpmb_dev as a host tool in soong makes it easy to package for
acloud, rather than building it in the Trusty build system and uploading
that to the remote instance.

Test: m
Bug: 354771029
Change-Id: I3b7f623238957ae3b25524d424025fd08f805657
diff --git a/trusty/utils/rpmb_dev/Android.bp b/trusty/utils/rpmb_dev/Android.bp
index 5e9caaf..603a1a8 100644
--- a/trusty/utils/rpmb_dev/Android.bp
+++ b/trusty/utils/rpmb_dev/Android.bp
@@ -18,12 +18,12 @@
 cc_binary {
     name: "rpmb_dev",
     vendor: true,
+    host_supported: true,
 
     srcs: [
         "rpmb_dev.c",
     ],
     shared_libs: [
-        "libc",
         "libcutils",
         "liblog",
         "libcrypto",