[epiphany] link to libexecinfo if needed

[Claudio Saavedra <csaavedra src gnome org>]

commit 9381141fb3d4fab540cc496ac51a8c082078a669
Author: Ting-Wei Lan <lantw44 gmail com>
Date:   Sun Jan 19 03:43:00 2014 +0000

    link to libexecinfo if needed
    
    https://bugzilla.gnome.org/show_bug.cgi?id=722521

 configure.ac |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index bd5b07e..28091a9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -128,6 +128,7 @@ AC_CHECK_FUNCS([localtime_r memchr memmove memset mkdir mkdtemp realpath sqrt st
 
 # for backtrace()
 AC_CHECK_HEADERS([execinfo.h fcntl.h])
+AC_SEARCH_LIBS([backtrace], [c execinfo])
 AC_C_INLINE
 AC_FUNC_MKTIME
 AC_FUNC_STRTOD