Erlang 27 compat: special case 0.0 (positive and negative) w/o using matching

Erlang 27 erlc requires us to match on both but earlier versions
complain that one head of the function is unreachable because the other
one always matches.

So we avoid pattern matching entirely.

Author: michaelklishin

deps/rabbit_common/src/rabbit_numerical.erl

@@ -30,9 +30,7 @@
 %%       human-readable output, or compact ASCII serializations for floats.
 digits(N) when is_integer(N) ->
     integer_to_list(N);
-digits(+0.0) ->
-    "0.0";
-digits(-0.0) ->
+digits(N) when N =:= 0.0 ->
     "0.0";
 digits(Float) ->
     {Frac1, Exp1} = frexp_int(Float),