MIPS: tools: Fix relocs tool compiler warnings

When using clang as HOSTCC, the following warnings appear:

In file included from arch/mips/boot/tools/relocs_64.c:27:0:
arch/mips/boot/tools/relocs.c: In function ‘read_relocs’:
arch/mips/boot/tools/relocs.c:397:4: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
    ELF_R_SYM(rel->r_info) = elf32_to_cpu(ELF_R_SYM(rel->r_info));
    ^~~~~~~~~
arch/mips/boot/tools/relocs.c:397:4: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
arch/mips/boot/tools/relocs.c: In function ‘walk_relocs’:
arch/mips/boot/tools/relocs.c:491:4: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
    Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)];
    ^~~~~~~
arch/mips/boot/tools/relocs.c: In function ‘do_reloc’:
arch/mips/boot/tools/relocs.c:502:2: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
  unsigned r_type = ELF_R_TYPE(rel->r_info);
  ^~~~~~~~
arch/mips/boot/tools/relocs.c: In function ‘do_reloc_info’:
arch/mips/boot/tools/relocs.c:641:3: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
   rel_type(ELF_R_TYPE(rel->r_info)),
   ^~~~~~~~

Fix them by making Elf64_Mips_Rela a union

Signed-off-by: Harvey Hunt <harvey.hunt@imgtec.com>
Acked-by: Matt Redfearn <matt.redfearn@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13683/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/boot/tools/relocs_64.c

@@ -9,17 +9,20 @@
 
 typedef uint8_t Elf64_Byte;
 
-typedef struct {
-	Elf64_Word r_sym;	/* Symbol index.  */
-	Elf64_Byte r_ssym;	/* Special symbol.  */
-	Elf64_Byte r_type3;	/* Third relocation.  */
-	Elf64_Byte r_type2;	/* Second relocation.  */
-	Elf64_Byte r_type;	/* First relocation.  */
+typedef union {
+	struct {
+		Elf64_Word r_sym;	/* Symbol index.  */
+		Elf64_Byte r_ssym;	/* Special symbol.  */
+		Elf64_Byte r_type3;	/* Third relocation.  */
+		Elf64_Byte r_type2;	/* Second relocation.  */
+		Elf64_Byte r_type;	/* First relocation.  */
+	} fields;
+	Elf64_Xword unused;
 } Elf64_Mips_Rela;
 
 #define ELF_CLASS               ELFCLASS64
-#define ELF_R_SYM(val)          (((Elf64_Mips_Rela *)(&val))->r_sym)
-#define ELF_R_TYPE(val)         (((Elf64_Mips_Rela *)(&val))->r_type)
+#define ELF_R_SYM(val)          (((Elf64_Mips_Rela *)(&val))->fields.r_sym)
+#define ELF_R_TYPE(val)         (((Elf64_Mips_Rela *)(&val))->fields.r_type)
 #define ELF_ST_TYPE(o)          ELF64_ST_TYPE(o)
 #define ELF_ST_BIND(o)          ELF64_ST_BIND(o)
 #define ELF_ST_VISIBILITY(o)    ELF64_ST_VISIBILITY(o)