[flang] [clang] [flang][Driver] Support -nodefaultlibs, -nostartfiles and -nostdlib (PR #72601)

[Andrzej Warzyński via cfe-commits]

================
@@ -1,5 +1,5 @@
-! Verify that certain linker flags are known to the frontend and are passed on
-! to the linker.
+! Verify that certain linker flags are known to the frontend and are passed or
+! not passed on to the linker.
----------------
banach-space wrote:

This updated comment is confusing. Could you just split it into two? 
```suggestion
! -------------------------------------------------------------------------------------------------
! 1: Default behaviour - verify that certain linker flags are known to the frontend and _are_ passed on 
! to the linker.
! -------------------------------------------------------------------------------------------------
(...)
! -------------------------------------------------------------------------------------------------
! 2: Non-default behaviour - verify that certain linker flags known to the frontend _are not_ passed on 
! to the linker when using e.g. `-nostdlib`.
! -------------------------------------------------------------------------------------------------
```

https://github.com/llvm/llvm-project/pull/72601