Could not find ottavation markup

[Dan Eble]

Using the latest version of master, I'm seeing the warning "Could not find 
ottavation markup for 1 octaves up" in a number of my scores when MIDI output 
is enabled.  This warning was added about a year ago in commit 
476194c706e4f9898fdbd5847dc1a924843f03e8 for Issue 5559.

How should this be addressed?  I can think of a few alternatives.

* define the markup in performer init (seems wrong)
* remove the warning
* before issuing the warning, check another property
  like in ab4f3cd2ad792b848c1045fd572b5f119a180d23

I lean toward removing the warning.
— 
Dan

\version "2.20.0"
\score {
 \fixed c' { \ottava #1 c1 }
 \midi { }
}