libsysprof-gtk: use 0 instead of -inf/inf

src/libsysprof-gtk/sysprof-axis.c

@@ -44,7 +44,7 @@ static double
 sysprof_axis_real_normalize (SysprofAxis  *axis,
                              const GValue *value)
 {
-  return -INFINITY;
+  return .0;
 }
 
 static void

src/libsysprof-gtk/sysprof-normalized-series.c

@@ -398,10 +398,10 @@ sysprof_normalized_series_get_value_at (SysprofNormalizedSeries *self,
   g_return_val_if_fail (SYSPROF_IS_NORMALIZED_SERIES (self), .0f);
 
   if (egg_bitset_contains (self->missing, position))
-    return -INFINITY;
+    return .0;
 
   if (position >= self->values->len)
-    return -INFINITY;
+    return .0;
 
   return g_array_index (self->values, float, position);
 }

src/libsysprof-gtk/sysprof-value-axis.c

@@ -81,7 +81,7 @@ get_as_double (const GValue *value)
       return g_value_get_double (&dst);
     }
 
-  return -INFINITY;
+  return .0;
 }
 
 static void