Change cpp to c file ahead of further extensions to the fuzzing test
harness.  This simplifies building afl-fuzz or with just C tools, but could be made C++ again if needed in the future.

Test: build and ran libFuzzer test
Bug: 239630493
Change-Id: I8873883ab5b91f36b707cd9d05856aa4c9c222bd
2 files changed