Remove benchmarks that use non-public APIs

These deleted benchmarks:
a) Use APIs not in the CorePlatformApi (and not ones we
want to add for any other reasons).
b) Are built with a .mk file.
c) Compile under the javac 8 build (because we reference
core-oj/core-libart) but do not compile under the javac 9
build (because AIUI .mk files do not allow us to specify
Java 9 system modules).

Because we use benchmarks mostly when checking in changes
to prove no regression for libcore changes there's no obligation
to fix this code: we can delete the troublesome ones.

Should somebody need the benchmarks in the future they can deal
with migrating the benchmark .mk to a .bp file, etc.

Bug: 117871421
Bug: 113148576
Test: make checkbuild (internal with OpenJDK 9 enabled)
Change-Id: I391ec9478eba5609021256c1b424e779fe97aa46
5 files changed