Changed size in seg_t struct from from an int* to an int.
Changed my_size_of() to just return the dereferenced size.  Works with changes to makeup of seg struct in seg.h
Changed new_seg() to support changes to seg struct.  We no longer write the integer into the start of the segment; just store it in the struct directly.
Changed all of my_malloc() to, unless using DEBUG, not move allocated segments to an allocation list.  Kept alloc_list usage in for debug printing, but otherwise alloc list is not used or necessary.