libc: don't export unnecessary symbols

Symbols associated with the internal implementation of memcpy
like routines should be private.

Change-Id: I2b1d1f59006395c29d518c153928437b08f93d16
diff --git a/libc/arch-arm/krait/bionic/__strcpy_chk.S b/libc/arch-arm/krait/bionic/__strcpy_chk.S
index 402cac6..1116cf6 100644
--- a/libc/arch-arm/krait/bionic/__strcpy_chk.S
+++ b/libc/arch-arm/krait/bionic/__strcpy_chk.S
@@ -163,7 +163,7 @@
 #define MEMCPY_BASE_ALIGNED __strcpy_chk_memcpy_base_aligned
 #include "memcpy_base.S"
 
-ENTRY(__strcpy_chk_failed)
+ENTRY_PRIVATE(__strcpy_chk_failed)
     .cfi_startproc
     .save   {r0, lr}
     .cfi_def_cfa_offset 8