Fix overlapping cfi ranges in mterp

Some residual .type and .size directives in mterp cause the
unwinder to see code covered by overlapping functions.  This
CL removes them, treating the mterp's assembly stubs as all
part of the same function.

Test: m test-art-host
Test: testrunner.py --host --interpreter
Bug: 66749877

Change-Id: Id4cebf140c3d4baa2298f1c56b66bad6686161ce