Add a server_jit_compile_time to the I_S.server-instance table to expose
this stat for use in testing.
merge tjoneslo: Add a server_jit_compile_time to the I_S.server-instance table

Merge pull request #1220 from tjoneslo/sql-layer/add-jit-compilation-time
https://github.com/FoundationDB/sql-layer/pull/1220