Update to 3.9.2
- New upstream release 3.9.2
- Minor speed-up when importing RSA (GH#328)
- Avoid allocating arrays of '__m128i' on the stack, to cope with buggy
compilers (GH#308)
- Remove blanket '-O3' optimization for gcc and clang, to cope with buggy
compilers (GH#322)
- Fix typing stubs for signatures (GH#337)
- Deal with gcc installations that don't have 'x86intrin.h' (GH#338)