swr: Fix crashes on non-AVX hardware

swr: Fix crashes on non-AVX hardware

Compilers may use vector instructions in calculating
hash values of std::string. This happens usualy when
high optimalization level is enabled. SWR had two
static std::map<std::string, T> variables which
lead to crashes on non-AVX systems during the initialization
of those variables. This commit makes those variables
dynamically allocated and fixes this AVX instruction
leak.

Closes: #3077
Closes: #198
Reviewed-by: Krzysztof Raszkowski <krzysztof.raszkowski@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6565>