Remove broken .so and fix bogus test.

Remove broken .so and fix bogus test.

valgrind doesn't like this because the .so *only* exists for x86 (contrary to
the claim in the @AndroidOnly annotation) but it's broken there, returning
a char* instead of a jstring.

I'm not really sure what they were trying to test here, but let's assume it
was that Runtime.getRuntime().load behaves like System.load, and fix the
tests that way.

Bug: 2223234