backtrace: Speculative fix for FreeBSD10.0 and execinfo.h
FreeBSD 10.0 ships an execinfo.h but one needs to link to an
additional library for the backtrace functions. Check if there
is a backtrace symbol in libexecinfo and if so link to that
library.
diff --git a/configure.ac b/configure.ac
index fbc83f3..eaaab50 100644
--- a/configure.ac
+++ b/configure.ac
@@ -36,6 +36,9 @@
AC_FUNC_ALLOCA
AC_SEARCH_LIBS([dlopen], [dl dld], [LIBRARY_DL="$LIBS";LIBS=""])
AC_SUBST(LIBRARY_DL)
+# for src/backtrace.c
+AC_CHECK_LIB(execinfo, backtrace, BACKTRACE_LIB=-lexecinfo, BACKTRACE_LIB=)
+AC_SUBST(BACKTRACE_LIB)
AC_PATH_PROG(DOXYGEN,doxygen,false)
AM_CONDITIONAL(HAVE_DOXYGEN, test $DOXYGEN != false)