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/__strcat_chk.S b/libc/arch-arm/krait/bionic/__strcat_chk.S
index 956b461..bb4bb86 100644
--- a/libc/arch-arm/krait/bionic/__strcat_chk.S
+++ b/libc/arch-arm/krait/bionic/__strcat_chk.S
@@ -196,7 +196,7 @@
 #define MEMCPY_BASE_ALIGNED __strcat_chk_memcpy_base_aligned
 #include "memcpy_base.S"
 
-ENTRY(__strcat_chk_failed)
+ENTRY_PRIVATE(__strcat_chk_failed)
     .cfi_startproc
     .save   {r0, lr}
     .save   {r4, r5}