encode_number: Ensure 64-bit alignment
encode_number: Ensure 64-bit alignment

This causes the 64-bit store to be aligned. On x86 and x86-64 this
should improve performance; on some other architectures, this should
prevent a byte-by-byte copy due to the misalignment.

Signed-off-by: Thiago Macieira <0ed1648d92ca0373297a182b1dba1b974ad10d88@intel.com>

intel/tinycbor,intel/tinycbor,thiagomacieira/tinycbor,01org/tinycbor,intel/tinycbor,01org/tinycbor,thiagomacieira/tinycbor,01org/tinycbor,thiagomacieira/tinycbor,intel/tinycbor,thiagomacieira/tinycbor