Clean up some fuzzer-related cruft.

The fuzzer can actually be built properly with Clang by overriding
`CXX`, `CXXFLAGS` and `LDFLAGS` as appropriate/desired. The "fake"
build and associated files are no longer useful if they ever were.

Change-Id: Ic47fbdac6ca6e9377fb1eb18ee12dcb2a96abc25
Reviewed-on: https://code-review.googlesource.com/c/re2/+/61970
Reviewed-by: Alex Chernyakhovsky <achernya@google.com>
Reviewed-by: Paul Wankadia <junyer@google.com>
4 files changed