Allow <sys/elf_common.h> to be used in assembly.

Hide C-only declarations under #ifndef LOCORE.  This will be used by
future changes to define ELF notes in assembly.

Reviewed by:	kib
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D25211

sys/sys/elf_common.h

@@ -46,12 +46,14 @@
  * not include the padding.
  */
 
+#ifndef LOCORE
 typedef struct {
 	u_int32_t	n_namesz;	/* Length of name. */
 	u_int32_t	n_descsz;	/* Length of descriptor. */
 	u_int32_t	n_type;		/* Type of this note. */
 } Elf_Note;
 typedef Elf_Note Elf_Nhdr;
+#endif
 
 /*
  * Option kinds.
@@ -112,12 +114,14 @@ typedef Elf_Note Elf_Nhdr;
  * The header for GNU-style hash sections.
  */
 
+#ifndef LOCORE
 typedef struct {
 	u_int32_t	gh_nbuckets;	/* Number of hash buckets. */
 	u_int32_t	gh_symndx;	/* First visible symbol in .dynsym. */
 	u_int32_t	gh_maskwords;	/* #maskwords used in bloom filter. */
 	u_int32_t	gh_shift2;	/* Bloom filter shift count. */
 } Elf_GNU_Hash_Header;
+#endif
 
 /* Indexes into the e_ident array.  Keep synced with
    http://www.sco.com/developers/gabi/latest/ch4.eheader.html */