Install vintf_fragments even when they are shared

Vintf_fragments should be installed regardless when they are shared with
other modules or not.

cc_binary {
  name: "foo",
  vintf_fragments: ["shared.xml"],
}

cc_binary {
  name: "bar",
  vintf_fragments: ["shared.xml"],
}

Either `m bar` or `m foo` should install `shared.xml`.

Previously, only *new* vintf_fragments were installed, which means, one
of "foo" or "bar" didn't trigger the installation of "shared.xml".

Bug: 198818343
Test: (see above)
Change-Id: I52b831df046b585db41449f06a6f9c684d623468