remove use of endian.h from arch reloc.h headers, clean up

building on commit 97d35a55,
__BYTE_ORDER is now available wherever alltypes.h is included. since
reloc.h is only used from src/internal/dynlink.h, it can be assumed
that __BYTE_ORDER is exposed. reloc.h is not permitted to be included
in other contexts, and generally, like most arch headers, lacks
inclusion guards that would allow such usage. the mips64 version
mistakenly included such guards; they are removed for consistency.

arch/aarch64/reloc.h

-#include <endian.h>
-
 #if __BYTE_ORDER == __BIG_ENDIAN
 #define ENDIAN_SUFFIX "_be"
 #else

arch/arm/reloc.h

-#include <endian.h>
-
 #if __BYTE_ORDER == __BIG_ENDIAN
 #define ENDIAN_SUFFIX "eb"
 #else

arch/microblaze/reloc.h

-#include <endian.h>
-
 #if __BYTE_ORDER == __LITTLE_ENDIAN
 #define ENDIAN_SUFFIX "el"
 #else

arch/mips/reloc.h

-#include <endian.h>
-
 #if __mips_isa_rev >= 6
 #define ISA_SUFFIX "r6"
 #else

arch/mips64/reloc.h

-#ifndef __RELOC_H__
-#define __RELOC_H__
-
-#define _GNU_SOURCE
-#include <endian.h>
-
 #if __mips_isa_rev >= 6
 #define ISA_SUFFIX "r6"
 #else
@@ -62,5 +56,3 @@
 	"	daddu %0, %0, $ra \n" \
 	".set pop \n" \
 	: "=r"(*(fp)) : : "memory", "ra" )
-
-#endif

arch/mipsn32/reloc.h

-#include <endian.h>
-
 #if __mips_isa_rev >= 6
 #define ISA_SUFFIX "r6"
 #else

arch/powerpc64/reloc.h

-#include <endian.h>
-
 #if __BYTE_ORDER == __LITTLE_ENDIAN
 #define ENDIAN_SUFFIX "le"
 #else

arch/s390x/reloc.h

-#include <endian.h>
-
 #define LDSO_ARCH "s390x"
 
 #define REL_SYMBOLIC    R_390_64

arch/sh/reloc.h

-#include <endian.h>
-
 #if __BYTE_ORDER == __BIG_ENDIAN
 #define ENDIAN_SUFFIX "eb"
 #else