Enable frame pointer in Redis compile options

This will make it easier to debug Redis performance issues. As seen in gitlab-com/gl-infra/production#939 (closed) and mentioned in http://www.brendangregg.com/perf.html:

Always compile with frame pointers. Omitting frame pointers is an evil compiler optimization that breaks debuggers, and sadly, is often the default. Without them, you may see incomplete stacks from perf_events.

Note that jemalloc inside Redis already compiles with this option on.

This actually decreased the binary size by 101,768 bytes for me.