Smaller handful of JIT-speed optimizations.

Summary: Optimize allocation in dce using a vector instead of linked list

inline some hot ir functions

Eval.JitRelocationSize defaults to 0 in opt builds, and 2^20 in debug builds.

optimize outputType()

partially inline subtypeOf

Reviewed By: @jdelong

Differential Revision: D1572492
remove extra newline

Reviewed By: @JoelMarcey, @fredemmott

Differential Revision: D1575599