Add missing symbols to android-17 libc

This affects libc.so for android-17 and 19

Symbols missing from NDK libc but present in the
platform version of libc:

__fgets_chk
__memcpy_chk
__memmove_chk
__memset_chk
__open_2
__openat_2
__snprintf_chk
__sprintf_chk
__strcat_chk
__strcpy_chk
__strlcat_chk
__strlcpy_chk
__strlen_chk
__strncat_chk
__strncpy_chk
__vsnprintf_chk
__vsprintf_chk
clone # x86 only
ftw
getsid
malloc_usable_size
mlockall
munlockall
nftw
psiginfo
psignal
pvalloc
unshare

Bug: http://b/28864994
Change-Id: I31ddaf44e2ae685d45de5ca217ba3096a3f6e5ec
12 files changed