cmpxchg16b instruction needs 16byte aligned data.
cmpxchg16b instruction needs 16byte aligned data.

Starting with DMD 2.067.1, the new atomicLoad() and atomicStore() functions are used.
At the core they use cmpxchg16b instruction which needs proper aligned data.

The shared HTTPServerContext[] is not properly aligned and causes a segmentation fault
with the upcoming LDC 0.16.0.

This PR adds align(16) to align the variable.

chalucha/vibe.d,DBankov/vibe.d,machindertechnologies/vibe.d,Geod24/vibe.d,rejectedsoftware/vibe.d,AndreyMZ/vibe.d,ColdenCullen/vibe.d,schuetzm/vibe.d,etcimon/vibe.d,gedaiu/vibe.d,Mihail-K/vibe.d,etcimon/vibe.d,redstar/vibe.d,yannick/vibe.d,mfrischknecht/vibe.d