[tor-dev] Compile warns

[grarpamp]

freebsd 12 x64 gcc 8.3.0

src/core/or/connection_edge.c:2563:5: warning: potential null pointer
dereference [-Wnull-dereference]
src/lib/math/fp.c:106:16: warning: conversion from 'double' to 'float'
may change value [-Wfloat-conversion]
src/lib/math/fp.c:111:18: warning: conversion from 'double' to 'float'
may change value [-Wfloat-conversion]
src/lib/math/fp.c:136:16: warning: conversion from 'double' to 'float'
may change value [-Wfloat-conversion]
src/lib/math/fp.c:88:13: warning: conversion from 'double' to 'float'
may change value [-Wfloat-conversion]