Use runtime_libs for the libdexfile_external dependency from
libdexfile_support.

It's a better specified dependency, and in particular it makes
linkerconfig pick it up and autogenerate the necessary links to the
com_android_art namespace where libdexfile_support is used.

Test: Build and boot, then check that
  /linkerconfig/com.android.runtime/ld.config.txt contains
  "namespace.default.link.com_android_art.shared_libs =
  libdexfile_external.so", which is necessary for
  /apex/com.android.runtime/bin/crash_dump{32,64} to find it.
Bug: 153996928
Change-Id: Ia56d7b85512369b0d642354c92540ba94c1debb1
diff --git a/libdexfile/Android.bp b/libdexfile/Android.bp
index 664fc1b..4f29689 100644
--- a/libdexfile/Android.bp
+++ b/libdexfile/Android.bp
@@ -364,7 +364,7 @@
     srcs: [
         "external/dex_file_supp.cc",
     ],
-    required: ["libdexfile_external"],
+    runtime_libs: ["libdexfile_external"],
     shared_libs: ["liblog"],
     header_libs: ["libdexfile_external_headers"],
     export_header_lib_headers: ["libdexfile_external_headers"],