swr: Fix non-pod-varargs error.

swr: Fix non-pod-varargs error.

../src/gallium/drivers/swr/rasterizer/jitter/functionpasses/lower_x86.cpp:391:24: error: cannot pass object of non-trivial type 'std::string' (aka 'basic_string<char>') through variadic function; call will abort at runtime [-Wnon-pod-varargs]
                       pFunc->getName().str());
                       ^

Fixes: ff8265b64ff1 ("gallium/swr: Fix llvm11 compilation issues")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Jan Zielinski <jan.zielinski@intel.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4008>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4008>