fmt getting installed on accident
fmt gets installed on accident with FEX now. That shouldn't happen. Noticed by a user.
```
-- Up-to-date: /usr/lib/aarch64-linux-gnu/libfmt.a
-- Up-to-date: /usr/include/fmt/args.h
-- Up-to-date: /usr/include/fmt/chrono.h
-- Up-to-date: /usr/include/fmt/color.h
-- Up-to-date: /usr/include/fmt/compile.h
-- Up-to-date: /usr/include/fmt/core.h
-- Up-to-date: /usr/include/fmt/format.h
-- Up-to-date: /usr/include/fmt/format-inl.h
-- Up-to-date: /usr/include/fmt/os.h
-- Up-to-date: /usr/include/fmt/ostream.h
-- Up-to-date: /usr/include/fmt/printf.h
-- Up-to-date: /usr/include/fmt/ranges.h
-- Up-to-date: /usr/include/fmt/std.h
-- Up-to-date: /usr/include/fmt/xchar.h
-- Up-to-date: /usr/lib/aarch64-linux-gnu/cmake/fmt/fmt-config.cmake
-- Up-to-date: /usr/lib/aarch64-linux-gnu/cmake/fmt/fmt-config-version.cmake
-- Up-to-date: /usr/lib/aarch64-linux-gnu/cmake/fmt/fmt-targets.cmake
-- Up-to-date: /usr/lib/aarch64-linux-gnu/cmake/fmt/fmt-targets-release.cmake
-- Up-to-date: /usr/lib/aarch64-linux-gnu/pkgconfig/fmt.pc
```
Maybe FEX's cmake just needs to set `FMT_INSTALL`?