[clang] [Sema] Warning for _Float16 passed to format specifier '%f' (PR #74439)

[Rainer Orth via cfe-commits]

rorth wrote:

This patch broke the [Solaris/sparcv9 buildbot](https://lab.llvm.org/buildbot/#/builders/72/builds/1709): the new/changed tests `FAIL` with
```
  File /opt/llvm-buildbot/home/solaris11-sparcv9/clang-solaris11-sparcv9/llvm/clang/test/SemaCXX/format-strings-scanf.cpp Line 25: _Float16 is not supported on this target
1 error generated.
```

https://github.com/llvm/llvm-project/pull/74439