Remove .symtab debug symbols for individual interpreted methods.

This code has been essentially moved to libunwindstack, which
will resolve the java method name by loading open dex files.

There is certainly no harm in having those entries in .symtab,
but as long as we do not use them, I am tempted to drop them.

Test: testrunner.py --host -t 137
Change-Id: If91ddec63cf2c27881148f56ef6fd4b533fef965