Fix support finding global variables.

The code was not properly getting the variable addresses and using
the offset and address fields of the .data section.

Fix all of that, and update the tests.

Bug: 145162678

Test: Unit tests pass.
Test: ./art/test/run-test --dex2oat-jobs 4 --host --prebuild --compact-dex-level fast --jit --no-relocate --runtime-option -Xcheck:jni  137-cfi
Test: ./art/test/testrunner/testrunner.py -t 137 --host
Change-Id: Ic61c4487334fd2273cda9c56eb1a3b525a03edb7