Revert^2 "Add CodeInfo to JNI methods."

It has no stack maps. We only store the frame info there.

As a consequence of having CodeInfo, the JNI methods are
now classified as IsOptimized().

This does not have any real effect on .oat file size.

This reverts commit 564fa8a1.

Test: test-art-host-gtest
Test: test-art-target-gtest-jni_compiler_test32
Change-Id: Ic7a1949027d89ba97cfedfc8ea453f041193b6a7