Add -XDskipDuplicateBridges=true flag to javac

Turbine leaves out bridges which can cause javac to unnecessarily insert
them into subclasses.  Setting this flag causes our custom javac to
assume that the missing bridges will exist at runtime and not recreate
them in subclasses.  If a different javac is used the flag will be
ignored and extra bridges will be inserted, which should be harmless.
The flag is implemented by https://android-review.googlesource.com/c/486427

Test: m -j checkbuild
Test: check core-libart for extra methods
Bug: 65645120
Change-Id: I6e2babe4a5a24cda4903845ae895c369343ec55b