Improve formatting of doubles that are close to integers

Now checks for approximate floating point equality so that more doubles
get properly disambiguated from integers

src/Desc.cc

@@ -164,7 +164,14 @@ void ODesc::Add(double d, bool no_exp)
 
 		Add(tmp);
 
-		if ( nearbyint(d) == d && isfinite(d) && ! strchr(tmp, 'e') )
+		auto approx_equal = [](double a, double b, double tolerance = 1e-6) -> bool
+			{
+			auto v = a - b;
+			return v < 0 ? -v < tolerance : v < tolerance;
+			};
+
+		if ( approx_equal(d, nearbyint(d), 1e-9) &&
+		     isfinite(d) && ! strchr(tmp, 'e') )
 			// disambiguate from integer
 			Add(".0");
 		}

testing/btest/Baseline/core.print-interval/out

@@ -8,12 +8,12 @@
 1.0 day 10.0 hrs 17.0 mins 36.0 secs 789.0 msecs 123.449984 usecs
 -1.0 day -10.0 hrs -17.0 mins -36.0 secs -789.0 msecs -123.449984 usecs
 1.001 usecs
-1.0 msec 1 usec
+1.0 msec 1.0 usec
 11.0 msecs
 8.0 days 12.0 hrs
 7.0 hrs 30.0 mins
 6.0 mins 30.0 secs
 5.0 secs 500.0 msecs
-4.0 msecs 500 usecs
+4.0 msecs 500.0 usecs
 3.5 usecs
 2.0 days 2.0 secs

testing/btest/Baseline/scripts.base.frameworks.logging.ascii-double/test.log

@@ -22,8 +22,8 @@
 178999999999999996376899522972626047077637637819240219954027593177370961667659291027329061638406108931437333529420935752785895444161234074984843178962619172326295244262722141766382622299223626438470088150218987997954747866198184686628013966119769261150988554952970462018533787926725176560021258785656871583744.0
 -178999999999999996376899522972626047077637637819240219954027593177370961667659291027329061638406108931437333529420935752785895444161234074984843178962619172326295244262722141766382622299223626438470088150218987997954747866198184686628013966119769261150988554952970462018533787926725176560021258785656871583744.0
 0.000012
-0
--0
+0.0
+-0.0
 inf
 -inf
 0.0

testing/external/commit-hash.zeek-testing

@@ -1 +1 @@
-da47ae786562da18910d994b7868530929db6271
+96e78328a1a9e6c07e725b282c293728f70737f0