crash building the documentation on 2.3.11

[Ferenc Wagner]

I built the program on Woody.  I had to add
#define _GNU_SOURCE
to the top of lily/slur-quanting.cc, otherwise the round()
function prototype wasn't imported.  Apart from that the
compilation went flawlessly, but building the docs bailed
out like:

Interpreting music... [3]
Preprocessing graphical objects...
Calculating line breaks...
paper output to `lily-435271871.tex'...
Now processing `lily-1416205702.ly'
Parsing...
Interpreting music... [6]
Preprocessing graphical objects...
Calculating line breaks... Backtrace:
In /usr/share/guile/1.6/srfi/srfi-1.scm:
 624: 48* [#<procedure #f (m)> (#<procedure override-markup #> # #)]
In /usr/local/src/lilypond/share/lilypond/scm/define-markup-commands.scm:
 128: 49  [Text_item::interpret_markup #< Output_def> (# # # ...) ...]
In unknown file:
   ?: 50* [override-markup #< Output_def> ((#) (# # #) (# # # ...) ...) ...]
In /usr/local/src/lilypond/share/lilypond/scm/define-markup-commands.scm:
 589: 51* [Text_item::interpret_markup #< Output_def> ((#) (#) (# # #) ...) ...]
In unknown file:
   ?: 52* [simple-markup #< Output_def> ((#) (#) (# # #) (# # # # ...) ...) "M"]
In /usr/local/src/lilypond/share/lilypond/scm/define-markup-commands.scm:
  37: 53* [Text_item::interpret_markup #< Output_def> ((#) (#) (# # #) ...) ...]
In unknown file:
   ?: 54* [#<procedure #f ()>]
In /usr/local/src/lilypond/share/lilypond/scm/font.scm:
 205: 55* [ly:font-load "msam10"]
In unknown file:
   ?: 56* [get-coding-table "TeX-math-symbols"]
In /usr/local/src/lilypond/share/lilypond/scm/encoding.scm:
 123: 57* [cadddr ...
 123: 58* [get-coding "TeX-math-symbols"]
 102: 59  (let ((entry #)) (if entry (cons # #) (if # # #)))
    ...
 103: 60  [cons "10037936.enc" ...
 103: 61* [force #<promise #<procedure #f ()>>]
In unknown file:
   ?: 62* [#<procedure #f ()>]
In /usr/local/src/lilypond/share/lilypond/scm/encoding.scm:
  74: 63* [get-coding-from-file "10037936.enc"]
  63: 64  (let* ((coding #) (com #) (vec #) (tab #)) (list com vec tab))
  63: 65* [read-encoding-file "10037936.enc"]
  15: 66  (let* ((raw #) (string #) (command #) ...) (cons command vector))
  15: 67* [ly:gulp-file #f]

/usr/local/src/lilypond/share/lilypond/scm/encoding.scm:15:15: In procedure 
ly_gulp_file in expression (ly:gulp-file (ly:kpathsea-expand-path filename)):
/usr/local/src/lilypond/share/lilypond/scm/encoding.scm:15:15: Wrong type 
argument in position 1 (expecting string): #f
lilypond-book: error: `lilypond' failed (status 2)
Traceback (most recent call last):
  File "../../scripts/lilypond-book.py", line 1087, in ?
  File "../../scripts/lilypond-book.py", line 1084, in main
  File "../../scripts/lilypond-book.py", line 1018, in do_file
  File "../../scripts/lilypond-book.py", line 1015, in process_include
  File "../../scripts/lilypond-book.py", line 1000, in do_file
  File "../../scripts/lilypond-book.py", line 831, in process_snippets
  File "/usr/local/src/lilypond/share/lilypond/python/lilylib.py", line 337, in 
system
    exit (1)
  File "/usr/local/src/lilypond/share/lilypond/python/lilylib.py", line 132, in 
exit
    raise _ ('Exiting (%d)...') % i
Exiting (1)...
make[4]: *** [out-www/lilypond.texi] Error 1
make[4]: Leaving directory `/usr/local/src/lilypond/Documentation/user'
make[3]: *** [WWW] Error 2
make[3]: Leaving directory `/usr/local/src/lilypond/Documentation'
make[2]: *** [WWW] Error 2
make[2]: Leaving directory `/usr/local/src/lilypond'
make[1]: *** [web] Error 2
make[1]: Leaving directory `/usr/local/src/lilypond'
make: *** [build-doc-stamp] Error 2

I can't get much out of this, but willing to help with
futher investigation as usual.
-- 
Thanks,
Feri.