Revert "Revert "ART: Fix up some multi-image cases""

This reverts commit de38b797c3e5ba3ee44c480db7093386975c51eb.

Fix up imgdiag for std::string and multi-image.

Bug: 26317072
Bug: 26320300

Change-Id: I94ce9528e9fea6fb3231a70c32db02d567143db9
diff --git a/tools/run-libcore-tests.sh b/tools/run-libcore-tests.sh
index 3c93f19..11ed8b9 100755
--- a/tools/run-libcore-tests.sh
+++ b/tools/run-libcore-tests.sh
@@ -79,7 +79,11 @@
     vogar_args="$vogar_args --vm-arg -Ximage:/data/art-test/core-optimizing.art"
     shift
   elif [[ "$1" == "--mode=host" ]]; then
-    vogar_args="$vogar_args --vm-arg -Ximage:${ANDROID_BUILD_TOP}/${OUT_DIR-out}/host/linux-x86/framework/core-jit.art"
+    # We explicitly give a wrong path for the image, to ensure vogar
+    # will create a boot image with the default compiler. Note that
+    # giving an existing image on host does not work because of
+    # classpath/resources differences when compiling the boot image.
+    vogar_args="$vogar_args --vm-arg -Ximage:/non/existent/vogar.art"
     shift
   elif [[ "$1" == "--debug" ]]; then
     # Remove the --debug from the arguments.