Clean up some misinformation around prctl.

prctl shouldn't be in <unistd.h>.

Change-Id: I29609fc91c033e1ad143b75d9b4eb17aefbd63d6
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 7ae054e..014d554 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -80,9 +80,7 @@
 int     setregid:setregid32(gid_t, gid_t)  arm,x86
 int     setregid:setregid(gid_t, gid_t)    arm64,mips,mips64,x86_64
 int     chroot(const char*)  all
-# IMPORTANT: Even though <sys/prctl.h> declares prctl(int, ...), the syscall stub must take 6 arguments
-#            to match the kernel implementation.
-int     prctl(int option, unsigned int arg2, unsigned int arg3, unsigned int arg4, unsigned int arg5) all
+int     prctl(int, unsigned long, unsigned long, unsigned long, unsigned long) all
 long    __arch_prctl:arch_prctl(int, unsigned long) x86_64
 int     capget(cap_user_header_t header, cap_user_data_t data) all
 int     capset(cap_user_header_t header, const cap_user_data_t data) all
diff --git a/libc/include/sys/prctl.h b/libc/include/sys/prctl.h
index 8c61677..d96b8b6 100644
--- a/libc/include/sys/prctl.h
+++ b/libc/include/sys/prctl.h
@@ -25,20 +25,16 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #ifndef _SYS_PRCTL_H
 #define _SYS_PRCTL_H
 
-#include <linux/prctl.h>
 #include <sys/cdefs.h>
 
+#include <linux/prctl.h>
+
 __BEGIN_DECLS
 
-/* IMPORTANT NOTE: This function is declared as taking a variable number
- *                 of arguments to match the GLibc definition. However
- *                 its declaration inside SYSCALLS.TXT *must* make it
- *                 take 6 arguments to ensure consistency with the kernel
- *                 implementation.
- */
 extern int prctl(int option, ...);
 
 __END_DECLS
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index afe5f1a..12e6257 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -71,9 +71,6 @@
 extern int execlp(const char *, const char *, ...);
 extern int execle(const char *, const char *, ...);
 
-/* IMPORTANT: See comment under <sys/prctl.h> about this declaration */
-extern int prctl(int  option, ...);
-
 extern int nice(int);
 
 extern int setuid(uid_t);