Prevents lilypond from segfaulting with add-footer = ##f (issue4832046)

[mtsolo]

Reviewers: ,

Message:
Fixes Issue 1796.

Cheers,
MS

Description:
Prevents lilypond from segfaulting with add-footer = ##f

Please review this at http://codereview.appspot.com/4832046/

Affected files:
  M lily/page-breaking.cc
  M lily/page-layout-problem.cc


Index: lily/page-breaking.cc
diff --git a/lily/page-breaking.cc b/lily/page-breaking.cc
index  
2e5854885e02eb432458442628696f329fb844e2..f81683a2573277f2de404409219cba8d31aef005  
100644
--- a/lily/page-breaking.cc
+++ b/lily/page-breaking.cc
@@ -577,7 +577,8 @@ Page_breaking::draw_page (SCM systems, SCM  
configuration, int page_num, int foot

   Page_layout_problem::add_footnotes_to_footer (footnotes, foot, book_);

-  p->set_property ("foot-stencil", foot->smobbed_copy ());
+  if (foot)
+    p->set_property ("foot-stencil", foot->smobbed_copy ());
   scm_apply_1 (page_stencil, page, SCM_EOL);

   return page;
Index: lily/page-layout-problem.cc
diff --git a/lily/page-layout-problem.cc b/lily/page-layout-problem.cc
index  
c9301ff3843f6812c1c39a129df9511c01817aca..57f5b61fba6edfd18d99623c31cb148578c7fe80  
100644
--- a/lily/page-layout-problem.cc
+++ b/lily/page-layout-problem.cc
@@ -277,6 +277,11 @@ Page_layout_problem::get_footnote_separator_stencil  
(Output_def *paper)
 void
 Page_layout_problem::add_footnotes_to_footer (SCM footnotes, Stencil  
*foot, Paper_book *pb)
 {
+  if (!foot)
+    {
+      warning ("Must have a footer to add footnotes.");
+      return;
+    }
   bool footnotes_found = false;
   Real footnote_padding = robust_scm2double (pb->paper_->c_variable  
("footnote-padding"), 0.0);
   Real footnote_footer_padding = robust_scm2double (pb->paper_->c_variable  
("footnote-footer-padding"), 0.0);