Snap for 8603585 from 2f7f57d587f1c6a1b0d02bbe0580ec18859993fc to mainline-conscrypt-release

Change-Id: I50ae3d09f09a9a8cea5884012b8c0f1ea3b12a22

lib/lib.h

diff --git a/lib/lib.h b/lib/lib.h
index 1721dd6..70e5bed 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -114,8 +114,8 @@
 // xwrap.c
 void xstrncpy(char *dest, char *src, size_t size);
 void xstrncat(char *dest, char *src, size_t size);
-void _xexit(void) __attribute__((__noreturn__));
-void xexit(void) __attribute__((__noreturn__));
+_Noreturn void _xexit(void);
+_Noreturn void xexit(void);
 void *xmmap(void *addr, size_t length, int prot, int flags, int fd, off_t off);
 void *xmalloc(size_t size);
 void *xzalloc(size_t size);
@@ -194,13 +194,13 @@
 void verror_msg(char *msg, int err, va_list va);
 void error_msg(char *msg, ...) printf_format;
 void perror_msg(char *msg, ...) printf_format;
-void error_exit(char *msg, ...) printf_format __attribute__((__noreturn__));
-void perror_exit(char *msg, ...) printf_format __attribute__((__noreturn__));
-void help_exit(char *msg, ...) printf_format __attribute__((__noreturn__));
+_Noreturn void error_exit(char *msg, ...) printf_format;
+_Noreturn void perror_exit(char *msg, ...) printf_format;
+_Noreturn void help_exit(char *msg, ...) printf_format;
 void error_msg_raw(char *msg);
 void perror_msg_raw(char *msg);
-void error_exit_raw(char *msg) __attribute__((__noreturn__));
-void perror_exit_raw(char *msg) __attribute__((__noreturn__));
+_Noreturn void error_exit_raw(char *msg);
+_Noreturn void perror_exit_raw(char *msg);
 ssize_t readall(int fd, void *buf, size_t len);
 ssize_t writeall(int fd, void *buf, size_t len);
 off_t lskip(int fd, off_t offset);