[ELFYAML] Provide explicit value for relocation addendums in the test

The `Addend` is an optional field of the `Relocation` YAML record. But
we do not provide its default value while reading it from a YAML file
and so it might keep uninitialized.

I am going to fix the code by a separate commit. We might either make
this field mandatory (at least for .rela sections) or specify 0 as
a default value explicitly.

llvm-svn: 227318

llvm/test/Object/Mips/elf-mips64-rel.yaml

@@ -79,17 +79,21 @@ Sections:
       - Offset:      0x20
         Symbol:      .rodata
         Type:        R_MIPS_GOT_PAGE
+        Addend:      0
       - Offset:      0x24
         Symbol:      .rodata
         Type:        R_MIPS_GOT_OFST
+        Addend:      0
       - Offset:      0x28
         Symbol:      printf
         Type:        R_MIPS_CALL16
+        Addend:      0
       - Offset:      0x30
         Symbol:      printf
         Type:        R_MIPS_GPREL16
         Type2:       R_MIPS_LO16
         SpecSym:     RSS_GP0
+        Addend:      0
   - Name:            .rodata
     Type:            SHT_PROGBITS
     Flags:           [ SHF_ALLOC ]