Configure /system/apex/com.android.runtime.[debug|release]/bin/*

When TARGET_FLATTEN_APEX is set to true, the APEXes are flattened
directly under /system/apex/<name>. Among them the runtime APEX carries
binaries such as linker, dex2oat and they need to be configured to be
executable.

Bug: 123684826
Test: Marlin/sailfish boots to the UI
Change-Id: I8ebe9dc4341410ff91ca2cb7cf95e21b0829c008