Inline helpers need to be exported unmangled.

__open_2() is used by the fortify implementation of open(2) in
fcntl.h, and as such needs an unmangled C name. For some reason
(inlining?), this doesn't cause problems at the default optimization
level, but does for -O0.

The rest of these didn't cause build failures, but they look suspect
and probably will, we just haven't caught them yet.

(cherry-pick of 658727e111 with conflicts
in stdio.h and string.h.)

Bug: 17784968
Change-Id: I7391a7a8999ee204eaf6abd14a3d5373ea419d5b

libc/include/unistd.h

@@ -197,12 +197,13 @@ extern int   tcsetpgrp(int fd, pid_t _pid);
     } while (_rc == -1 && errno == EINTR); \
     _rc; })
 
-#if defined(__BIONIC_FORTIFY)
 extern ssize_t __read_chk(int, void*, size_t, size_t);
 __errordecl(__read_dest_size_error, "read called with size bigger than destination");
 __errordecl(__read_count_toobig_error, "read called with count > SSIZE_MAX");
 extern ssize_t __read_real(int, void*, size_t) __RENAME(read);
 
+#if defined(__BIONIC_FORTIFY)
+
 __BIONIC_FORTIFY_INLINE
 ssize_t read(int fd, void* buf, size_t count) {
     size_t bos = __bos0(buf);