Do not make lack of SSE2 support on x86-32 fatal

Do not make lack of SSE2 support on x86-32 fatal

When an x86-32 CPU does not have SSE2 support (which is the case for
all AMD CPUs, and older Intel CPUs), fallback to use the interpreter,
otherwise use the JIT engine.

Even then, make the lack of SSE2 support on x86-32 fatal when trying
to instantiate a JIT engine, which does require it.

Refactor the required CPU support check into a new pair of privately
exported functions to avoid duplicating the logic, and do so in
functions instead of class members to avoid changing the class
signatures.

Version: 5.7.x
Bug-Debian: https://bugs.debian.org/792594

Gbp-Pq: Name Do-not-make-lack-of-SSE2-support-on-x86-32-fatal.patch