Rename __bionic_clone_entry to __start_thread.

This seems a bit less obscure.

Change-Id: I7dc528c253b73c861694f67556ad8f919bf92136
diff --git a/libc/arch-x86/bionic/__bionic_clone.S b/libc/arch-x86/bionic/__bionic_clone.S
index 0c0feff..917dc68 100644
--- a/libc/arch-x86/bionic/__bionic_clone.S
+++ b/libc/arch-x86/bionic/__bionic_clone.S
@@ -39,7 +39,7 @@
 .L_bc_child:
         # We don't want anyone to unwind past this point.
         .cfi_undefined %eip
-        call    __bionic_clone_entry
+        call    __start_thread
         hlt
 
 .L_bc_parent: