to make it easier to write portable acid code, we
introduce 'A' format in the same meaning as in db(1):
A Print the value of dot in hexadecimal. Dot is
unaffected.
both 'a' (symbolic) and 'A' will both have 64 or 32 bit
size depending on the mach, so pointer array indexing
works the same.
we cannot call gc() in execute() because it will gc
anonyous intermediate results which happens when we
construct a list and the elements are calculated by
calling a function thru ocall() which calls execute().
also, the _thiscmd symbol; which is used to keep
a reference to a statement so it wont get garbage
collected; does not work as yyparse() is recursive
(include statements).
we add execrec() function which *only* gets called from
yyparse() when evaluating a statement. it will
keep a stack on the _thiscmd symbol handling the yyparse()
recursion.
we also only call gc() in execrec() before calling
execute(). so execute() will never gc() while evaluating
a statement which prevents the intermediate results
from getting collected.
