Rename __arch_prctl() to arch_prctl().

This matches glibc, but this change doesn't actually expose the symbol publicly. glibc's in a weird position where the symbol is exposed, but there's no declaration in their headers, and I'd like to try to resolve that in glibc first (even if that resolution is "WAI").

Change-Id: I2f210a0eeae82ec697801ef88476177022ad4222

Author: enh-google

libc/SYSCALLS.TXT

@@ -88,7 +88,6 @@ int     setregid:setregid32(gid_t, gid_t)  lp32
 int     setregid:setregid(gid_t, gid_t)    lp64
 int     chroot(const char*)  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
 int     sigaltstack(const stack_t*, stack_t*) all
@@ -366,6 +365,7 @@ int __riscv_flush_icache:riscv_flush_icache(void*, void*, unsigned long) riscv64
 
 # x86-specific
 int     __set_thread_area:set_thread_area(void*) x86
+long arch_prctl(int, unsigned long) x86_64
 
 # vdso stuff.
 int __clock_getres:clock_getres(clockid_t, struct timespec*) all

libc/arch-x86_64/bionic/__set_tls.c

@@ -27,11 +27,12 @@
  */
 
 #include <sys/cdefs.h>
+
+// ARCH_SET_FS is not exposed via <sys/prctl.h> or <linux/prctl.h>.
 #include <asm/prctl.h>
-#include <stdint.h>
 
-extern int __arch_prctl(int, unsigned long);
+extern int arch_prctl(int, unsigned long);
 
 __LIBC_HIDDEN__ int __set_tls(void* ptr) {
-  return __arch_prctl(ARCH_SET_FS, (uintptr_t) ptr);
+  return arch_prctl(ARCH_SET_FS, (unsigned long) ptr);
 }