Remove method cache from libdexfile_external.

Equivalent cache has been added to libunwind (go/aog/1647434).

This gives libunwind control of the string storage format,
and other memory vs speed trade-offs.

Bug: 123517037
Test: test.py -r -b --host -t 137
Change-Id: I3cbd10ba513ca3cfae3addbea6a8de05b0906b30
1 file changed