libbacktrace patch committed: Check for sys/link.h

[Ian Lance Taylor via Gcc-patches]

Apparently QNX declares dl_iterate_phdr and friends in sys/link.h
rather than link.h.  This patch updates libbacktrace to check there.
This fixes https://github.com/ianlancetaylor/libbacktrace/issues/86.
Bootstrapped and ran libbacktrace testsuite on x86_64-pc-linux-gnu.
Committed to mainline.

Ian

* configure.ac: Check for sys/link.h.  Use either link.h or
sys/link.h when checking for dl_iterate_phdr.
* elf.c: Include sys/link.h if available.
* configure, config.h.in: Regenerate.

bab8b6e52fb0b48b5d9d1af5f93e5c8fb20d6240
diff --git a/libbacktrace/configure.ac b/libbacktrace/configure.ac
index 857987a2859..1daaa2f62d2 100644
--- a/libbacktrace/configure.ac
+++ b/libbacktrace/configure.ac
@@ -335,13 +335,17 @@ fi
 AC_SUBST(BACKTRACE_USES_MALLOC)
 
 # Check for dl_iterate_phdr.
-AC_CHECK_HEADERS(link.h)
-if test "$ac_cv_header_link_h" = "no"; then
+AC_CHECK_HEADERS(link.h sys/link.h)
+if test "$ac_cv_header_link_h" = "no" -a "$ac_cv_header_sys_link_h" = "no"; 
then
   have_dl_iterate_phdr=no
 else
   if test -n "${with_target_subdir}"; then
+    link_h=link.h
+    if test "$ac_cv_header_link_h" = "no"; then
+       link_h=sys/link.h
+    fi
     # When built as a GCC target library, we can't do a link test.
-    AC_EGREP_HEADER([dl_iterate_phdr], [link.h], [have_dl_iterate_phdr=yes],
+    AC_EGREP_HEADER([dl_iterate_phdr], [$link_h], [have_dl_iterate_phdr=yes],
                    [have_dl_iterate_phdr=no])
   else
     AC_CHECK_FUNC([dl_iterate_phdr], [have_dl_iterate_phdr=yes],
diff --git a/libbacktrace/elf.c b/libbacktrace/elf.c
index 8b82dd45875..181d195fe35 100644
--- a/libbacktrace/elf.c
+++ b/libbacktrace/elf.c
@@ -40,7 +40,12 @@ POSSIBILITY OF SUCH DAMAGE.  */
 #include <unistd.h>
 
 #ifdef HAVE_DL_ITERATE_PHDR
-#include <link.h>
+ #ifdef HAVE_LINK_H
+  #include <link.h>
+ #endif
+ #ifdef HAVE_SYS_LINK_H
+  #include <sys/link.h>
+ #endif
 #endif
 
 #include "backtrace.h"