LibC+LibELF: Implement support for the dl_iterate_phdr helper

This helper is used by libgcc_s to figure out where the .eh_frame sections
are located for all loaded shared objects.

Userland/Tests/Kernel/elf-symbolication-kernel-read-exploit.cpp

@@ -24,7 +24,8 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <LibELF/exec_elf.h>
+#include <AK/Types.h>
+#include <elf.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <string.h>