Micro-optimisation: Merge append_byte_to_buffer with append_to_buffer
Micro-optimisation: Merge append_byte_to_buffer with append_to_buffer

This makes the cborencoder.o only 986 bytes with -Os on x86-64. The
function is still inlined with -O2.

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

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