tiny-pf: tiny printf function for x86_64

about:
	this is a small implementation of printf function from libc but for x86_64 so i
	do not have to use any other library for my x86_64 projects :). It is pretty
	simple to use:

	1. provide fd via rdi
	2. provide format string via rsi
	3. provide arguments via stack (reverse order)

features:
	formats:
		%d for integers
		%c for characters
		%s for null terminated strings
		%b for boolean
		%% literal %
	alignment:
		%<sizeFORMAT  left-align
		%>sizeFORMAT right-align

		size can be a literal like %<10d (left 10 padding integer) or
		a variable padding given via argument on the stack %<#d

notes:
	- no thread safe
	- 4096 b buffer (do not worry about overflow tho)
	- depends on xvargs library
	- the caller is responsable for adding $N to rsp after calling
	- if TINY_PF_LONG_BOOL_FMT macro is defined, then the boolean
	  values will be 'true' and 'false', 'T' or 'F' will be used otherwise