The Flang :: Driver/lto-flags.f90 test FAILs on Solaris:
/vol/llvm/src/llvm-project/dist/flang/test/Driver/lto-flags.f90:30:13: error: THIN-LTO: expected string not found in input ! THIN-LTO: "-plugin-opt=thinlto" ^
This is no wonder since the native Solaris ld doesn't support the linker plugin interface at all, so this patch marks the test as UNSUPPORTED.
Tested on amd64-pc-solaris2.11 and x86_64-pc-linux-gnu.