Remove platform from apex_available for dexdump.

Since apex_available applies to all targets it makes us use the APEX
stubs for libdexfile when building the device variant for platform when
https://r.android.com/1664027 lands. The platform availability should
only apply for host in SDK builds, so the device variant isn't actually
used anywhere, but it still fails in checkbuild.

This availability doesn't appear to be strictly necessary, possibly
because the dependency when building the SDK is from make.

Test: m nothing
Test: m TARGET_PRODUCT=sdk TARGET_BUILD_VARIANT=userdebug sdk
Test: m TARGET_PRODUCT=sdk TARGET_BUILD_VARIANT=userdebug win_sdk
Bug: 143978909
Change-Id: I0027bf931c0f5e05f43aee91c9fb77fd436777d6
diff --git a/dexdump/Android.bp b/dexdump/Android.bp
index 88bcb30..3b651e8 100644
--- a/dexdump/Android.bp
+++ b/dexdump/Android.bp
@@ -64,7 +64,6 @@
     apex_available: [
         "com.android.art",
         "com.android.art.debug",
-        "//apex_available:platform", // for SDK
     ],
 }