finding problem in issue 2990

[Yevgeny Lezhnin]

issue 2990 : lilypond crashes with a stack overflow on Windows (1)
also tested in Linux, also crash

There is infinite loop in calc_skylines function, I don't know yet, what 
may cause it.

This is quotes from discussion with Mike Solomon:

I get this backtrace running gdb lilypond with sample from issue 2990:
#0  0xb79aa0ac in ?? () from /lib/i386-linux-gnu/libc.so.6
#1  0xb79acddc in malloc () from /lib/i386-linux-gnu/libc.so.6
#2  0xb7b8cdb7 in operator new(unsigned int) ()
   from /usr/lib/i386-linux-gnu/libstdc++.so.6
#3  0x0823e328 in allocate (this=<optimized out>, __n=<optimized out>)
    at /usr/include/c++/4.7/ext/new_allocator.h:94
#4  _M_get_node (this=<optimized out>)
    at /usr/include/c++/4.7/bits/stl_list.h:335
#5  _M_create_node (__x=..., this=<optimized out>)
    at /usr/include/c++/4.7/bits/stl_list.h:482
#6  _M_insert (__x=..., __position=..., this=<optimized out>)
    at /usr/include/c++/4.7/bits/stl_list.h:1525
#7  push_back (__x=..., this=0xbf800128)
    at /usr/include/c++/4.7/bits/stl_list.h:997
#8  Skyline::Skyline (this=0xbf800128, src=...) at skyline.cc:463
#9  0x0807e356 in Drul_array (this=0xbf800128)
    at ../flower/include/drul-array.hh:30
#10 Skyline_pair (this=0xbf800128) at ./include/skyline-pair.hh:25
#11 add_interior_skylines (me=0x844c6c8, address@hidden,
    address@hidden, address@hidden)
    at axis-group-interface.cc:632
#12 0x0807e474 in add_interior_skylines (me=0x845fcd8,
    address@hidden, address@hidden,
---Type <return> to continue, or q <return> to quit---

and so on add_interior_skylines (more then 5000 entries)

(gdb) bt -5
#87233 0x0807e4e4 in add_interior_skylines (me=0x8705e78,
    address@hidden, address@hidden,
    address@hidden) at axis-group-interface.cc:624
#87234 0x0807e4e4 in add_interior_skylines (me=0x8709880, 
x_common=0x852fd20,
    y_common=0x8705e78, skylines=0xbfffc6ac) at axis-group-interface.cc:624
#87235 0x08080144 in Axis_group_interface::skyline_spacing (me=0x8705e78,
    elements=...) at axis-group-interface.cc:881
#87236 0x080803ad in Axis_group_interface::calc_skylines (smob=0xb6e06408)
    at axis-group-interface.cc:397
#87237 0xb6e06408 in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt stack?)

1) 
http://code.google.com/p/lilypond/issues/detail?id=2990&colspec=ID%20Type%20Status%20Stars%20Owner%20Patch%20Needs%20Summary