[MIPS64] JNI Compiler: compiler independent test

Fixed MIPS64 stackArgsSignExtendedTest that did not work properly
when code was built with clang. The the test is now written in an
asm stub and should be completely compiler indepedent.

Test: mma test-art-target-gtest-jni_compiler_test

Change-Id: Idefef3a8414dd8b88a28d2d8862a724bc72402a7
2 files changed