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The Intel C++ Compiler (ICX) passes linker flags through the driver
unlike MSVC and clang-cl, and therefore needs them to be prefixed with
`/Qoption,link` (the equivalent of `-Wl,` for gcc on *nix).
Use `LINKER:` prefix wherever supported by cmake, when that's not
possible fall-back to `${CMAKE_CXX_LINKER_WRAPPER_FLAG}`. CMake replaces
these with `/Qoption,link` for ICX and with the empty string for MSVC
and clang-cl.
For `target_link_libraries` neither `LINKER:` (not supported prior to
CMake 3.32) nor `${CMAKE_CXX_LINKER_WRAPPER_FLAG}` (does not begin with
`-` would be taken as a library name) works, use `-Qoption,link`
directly within a conditional generator expression that we're linking
with ICX.
For MSVC and clang-cl no functional change is intended.
Tested by compiling with ICX and setting
`CMAKE_(EXE|SHARED|STATIC|MODULE)_LINKER_FLAGS_INIT` to
`-Werror=unknown-argument`.
RFC:
https://discourse.llvm.org/t/rfc-cmake-linker-flags-need-wl-equivalent-for-intel-c-icx-on-windows/82446
See docs/CMake.html for instructions on how to build LLVM with CMake.