[foreign-memaccess+abi] RFR: Fix tests using stale `SymbolLookup::lookup`

[Maurizio Cimadamore]

This simple patch fixes a couple of tests that were missed during https://git.openjdk.org/panama-foreign/pull/716

-------------

Commit messages:
 - Fix tests using stale `SymbolLookup::lookup`

Changes: https://git.openjdk.org/panama-foreign/pull/722/files
 Webrev: https://webrevs.openjdk.org/?repo=panama-foreign&pr=722&range=00
  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/panama-foreign/pull/722.diff
  Fetch: git fetch https://git.openjdk.org/panama-foreign pull/722/head:pull/722

PR: https://git.openjdk.org/panama-foreign/pull/722