ldconfig-native: Add 64-bit flag for ELF64 entries

ldconfig-native: Add 64-bit flag for ELF64 entries

ldconfig-native was grepped from an old version of glibc, and its output
lacks neccessary 64bit flag in entries.
Due to this defect, ctypes.util.find_library() python function fails to
detect any library due to the old file format that ldconfig-native
creates. This fix sets architecture-dependent 64bit flags for 64-bit ELF.

Since the host's elf.h may not have definition for new AArch64 machine
type, a work-around is added to correctly flag 64-bit ARM libraries.

Signed-off-by: Yuanjie Huang <yuanjie.huang@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>