Don't check the Host ART APEX when `HOST_PREFER_32_BIT` is `true`.

The Host ART APEX (`com.android.art.host`) is not built when
`HOST_PREFER_32_BIT` equals `true`; remove it from the list of ART
APEXes verified by the `build/apex/runtests.sh` script.

Test: env HOST_PREFER_32_BIT=true art/build/apex/runtests.sh
Test: env HOST_PREFER_32_BIT=false art/build/apex/runtests.sh
Change-Id: I4984212b70d8c231884bd85682a213532c7e5407
diff --git a/build/apex/runtests.sh b/build/apex/runtests.sh
index c3dc709..72bf74b 100755
--- a/build/apex/runtests.sh
+++ b/build/apex/runtests.sh
@@ -124,14 +124,18 @@
   exit_status=1
 }
 
-# Test all modules
+# Test all modules, if possible.
 
 apex_modules=(
   "com.android.art.release"
   "com.android.art.debug"
   "com.android.art.testing"
-  "com.android.art.host"
 )
+if [[ "$HOST_PREFER_32_BIT" = true ]]; then
+  say "Skipping com.android.art.host, as \`HOST_PREFER_32_BIT\` equals \`true\`"
+else
+  apex_modules+=("com.android.art.host")
+fi
 
 # Build the APEX packages (optional).
 build_apex ${apex_modules[@]}