Rename __bionic_clone_entry to __start_thread.

This seems a bit less obscure.

Change-Id: I7dc528c253b73c861694f67556ad8f919bf92136
diff --git a/libc/arch-x86_64/bionic/__bionic_clone.S b/libc/arch-x86_64/bionic/__bionic_clone.S
index 173ab5c..e0ce5a6 100644
--- a/libc/arch-x86_64/bionic/__bionic_clone.S
+++ b/libc/arch-x86_64/bionic/__bionic_clone.S
@@ -62,12 +62,12 @@
         .cfi_undefined %rip
         .cfi_undefined %rbp
 
-        # We're in the child now, so call __bionic_clone_entry
+        # We're in the child now, so call __start_thread
         # with the arguments from the child stack moved into
         # the appropriate registers.
         popq    %rdi  # fn
         popq    %rsi  # arg
-        call    __bionic_clone_entry
+        call    __start_thread
         hlt
 
 .L_bc_parent: