libobs/util: Do not include SIMDe for MinGW targets
MinGW comes with it's own intrinsics macros as regular MSVC does.
On MinGW the inclusion of SIMDe would cause multiple definitions
of the same macro names.
Since sse-intrin.h leaks into the public header space this
will cause 3rd party plugins build with MinGW tool-chains emit
redeclaration warnings when including obs-module.h.
Florian Zwoch