MaxScaleUptime() renamed to maxscale_uptime() and moved from
gateway.c (MaxScale main) to misc.c, which is included in the
maxscale_common library. That way the symbol will be available
at link-time and will thus not prevent the use of the linker
flags -Wl,-z,defs (resolve all symbols at link-time) when
linking a module that uses maxscale_uptime().