PATCH BFD section load page support

[Timothy Wall]

Now I remember why I didn't extend "OVERLAY".

OVERLAY takes a given defined region of memory and puts any number of sections
within it, much like the "union" construct in C.  This presumes that all of
your "overlay" memory regions are identical.

In the case of the C54x (and numerous other DSPs), the memory regions which are
"overlaid" may have no resemblance at all to one another.  For instance, here
is the layout of one particular configuration, showing PAGE 0 and PAGE 1, which
have several memory "regions" within them.  It is usually desired to make
optimum use of *all* memory regions; note that the OVERLAY mechanism doesn't
apply very well in this case, because the address ranges that are "overlaid"
have different ranges on the different pages.  Applying a "page" extension to
memory regions, however, fits this model quite nicely.

Program memory (PAGE 0)
0x0000-0x007F external
0x0080-0x13FF on-chip DARAM
0x1400-0x8FFF external
0x9000-0xFF7F ROM
0xFF80-0xFFFF interrupt vectors

Data memory (PAGE 1)
0x0000-0x005F memory-mapped registers
0x0060-0x007F scratch-pad DARAM
0x0080-0x13FF on-chip DARAM
0x1400-0xDFFF external
0xE000-0xFEFF on-chip ROM
0xFF00-0xFFFF reserved