avoid C99 %z printf format spec in asn1 gen_decode
avoid C99 %z printf format spec in asn1 gen_decode

Windows does not support the %z printf format specification
indicating the variable is of size_t.  In gen_decode the
variable 'depth' does not need to be of 'size_t'.  'unsigned int'
will suffice.

Change-Id: Ic56290ba702f7681d5e11f9d23bfa3eb7274dbbe

madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal,madscientist159/heimdal