Install symlink to the runtime APEX only for device

Host does not need the symlink. It also broke master-art-host targets.

Test: ALLOW_MISSING_DEPENDENCIES=true
DIST_DIR=~/temp
./art/tools/dist_linux_bionic.sh -j50 showcommands
com.android.runtime.host

Change-Id: Ie8e02553c5a1b6cd5afebd73a64268d2950fc18e
diff --git a/cc/library.go b/cc/library.go
index 6404906..5df5112 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -920,7 +920,9 @@
 			// The original path becomes a symlink to the corresponding file in the
 			// runtime APEX.
 			if isBionic(ctx.baseModuleName()) && !library.buildStubs() && ctx.Arch().Native && !ctx.inRecovery() {
-				library.installSymlinkToRuntimeApex(ctx, file)
+				if ctx.Device() {
+					library.installSymlinkToRuntimeApex(ctx, file)
+				}
 				library.baseInstaller.subDir = "bootstrap"
 			}
 		}