Add define for DT_MIPS_XHASH (MIPS gnu hash support) using system elf.h header.
Bug: https://bugs.gentoo.org/860888
--- /dev/null
+++ b/src/elf.h
@@ -0,0 +1,4 @@
+#include_next <elf.h>
+#ifndef DT_MIPS_XHASH
+#define DT_MIPS_XHASH 0x70000036
+#endif