Add NT_PRSTATUS to <elf.h>.

Needed by aarch64.

Bug: 12476126
Change-Id: I7764664459a06cf4f2a60e707bd968d321a78430

libc/include/elf.h

@@ -30,6 +30,8 @@
 
 #include <stdint.h>
 #include <linux/auxvec.h>
+
+/* TODO: can we switch to <linux/elf.h> instead? http://b/12476126. */
 #include <sys/exec_elf.h>
 
 typedef struct {
@@ -52,4 +54,7 @@ typedef struct {
 #  define Elf_auxv_t Elf32_auxv_t
 #endif
 
+/* <sys/exec_elf.h> doesn't contain any NT_ constants. aarch64 strace needs this one. */
+#define NT_PRSTATUS 1
+
 #endif /* _ELF_H */

linker/linker.h

@@ -29,12 +29,9 @@
 #ifndef _LINKER_H_
 #define _LINKER_H_
 
-#include <unistd.h>
-#include <sys/types.h>
 #include <elf.h>
-#include <sys/exec_elf.h>
-
 #include <link.h>
+#include <unistd.h>
 
 #include "private/libc_logging.h"