ocamloptp shouldn't be compiled in bytecode-only mode

[dra27]

Spotted while reviewing #10265. I haven't chased down whether this has always been wrong if it's a regression from the build system merge PRs, but tools/ocamloptp is compiled even if the tree is configured with --disable-native-compiler. It - and profiling.cmx should only be built during make opt.

[github-actions]

This issue has been open one year with no activity. Consequently, it is being marked with the "stale" label. What this means is that the issue will be automatically closed in 30 days unless more comments are added or the "stale" label is removed. Comments that provide new information on the issue are especially welcome: is it still reproducible? did it appear in other contexts? how critical is it? etc.