Use more prebuilt build-tools

For acp, we've been using an old prebuilt in prebuilts/sdk, but it's not
part of the SDK. Instead, we'll use a prebuilt in the build-tools
repository.

For ijar, we've been using the host libstdc++ to workaround the lack of
libc++ on some unbundled branches. Instead, use a prebuilt that can use
libc++.

For ziptime, we've been disabling it on unbundled branches, due to the
lack of libc++. Instead, use a prebuilt version of ziptime that can use
the prebuilt libc++.

Change-Id: If80f845ea06f76e3fe6765964e77c864eaf303d0

tools/ijar/Android.bp

@@ -15,20 +15,4 @@ cc_binary_host {
     ],
     host_ldlibs: ["-lz"],
     name: "ijar",
-    // libc++ is not supported for TARGET_BUILD_APPS builds
-    stl: "libstdc++",
-}
-
-cc_binary_host {
-    srcs: [
-        "classfile.cc",
-        "ijar.cc",
-        "zip.cc",
-    ],
-    cflags: [
-        "-Wall",
-        "-Werror",
-    ],
-    host_ldlibs: ["-lz"],
-    name: "ijar_libc++",
 }