MIPS/LD/testsuite: Run HI16/LO16 tests for VxWorks too

Run ELF linker tests for HI16/LO16 relocations with MIPS/VxWorks targets
as well.  Despite issues only fixed in the next change they produce the
same results as with other MIPS targets, so just use the existing tests
verbatim, however refrain from adding other tests until said issues have
been fixed.

ld/testsuite/ld-mips-elf/mips-elf.exp

@@ -45,6 +45,12 @@ if {[istarget "mips*-*-vxworks"]} {
     run_ld_link_tests $mipsvxtests
     run_dump_test "vxworks1-static"
     run_dump_test "vxworks-forced-local-1"
+
+    run_dump_test "mips-hilo"
+    run_dump_test "mips16-hilo"
+    run_dump_test "mips16e2-hilo"
+    run_dump_test "micromips-hilo"
+    run_dump_test "pcrel-hilo"
     return
 }