[Driver] Use AddRunTimeLibs on Solaris (#137596)
When linking `libomp.so` on Solaris, I encountered
```
clang: warning: argument unused during compilation: '-static-libgcc' [-Wunused-command-line-argument]
```
This happens because `Solaris.cpp` (`solaris::Linker::ConstructJob`)
links `-lgcc_s` and `-lgcc` on its own instead of using the common
`CommonArgs.cpp` (`tools::AddRunTimeLibs`) which handles
`-static-libgcc` out of the box.
This patch switches to `AddRunTimeLibs` and adds a test for
`-static-libgcc` handling. In `solaris-ld.c`, a few tests had to be
adjusted because `-lgcc` is now linked before `-lgcc_s`.
Tested on `amd64-pc-solaris2.11` and `sparcv9-sun-solaris2.11`.
