btstack_ring_buffer: remove duplicate definition

license: update text

avoid function param modification

examples: use `btstack_event.h` getters instead of direct array access, use enum to compare status codes

MISRAC2012-Rule-14.4_c: compare against 0 or NULL

btstack_ring_buffer: add btstack_ring_buffer_reset to reset it to initial state/empty

MISRAC2012-Rule-10.4_a: append 'u' to constant literals when used in unsigned expressions or comparisons

remove <stdio.h>, <stdlib.h> and printf from most core files

ignore memcpy return value (always returns first parameter)

Use BTSTACK_FILE__ without __ prefix (MISRAC2012-Rule-21.1)

btstack_ring_buffer: fix corner cases for empyt/full buffer and data length == 0

btstack_ring_buffer: use uint32_t for sizes

tool: add update_filename.py that adds __BTSTACK_FILE__ to every .c file for use with debug output instead of __FILE__

Ring Buffer: speed up by using memcpy

extend ring buffer indexes from uint16 to uint32

fix ring buffer read

add ring buffer implementation