Continuing the theme from the first part, the optimized assembly files
for x86-64 and i386 include their own private copies of
jpeg_nbits_table. There's no need for them to do so; they can make use
of the C copy that we commonized in the first patch.
The current setup means that including jpeg_nbits_table.h creates a 64K
static table in the current compilation unit...for every inclusion of
jpeg_nbits_table.h. Since we have two such inclusions, we have two
copies of this table, and the linker is not merging them; perhaps there
is a limit on the size of identical blobs of data it will merge.
In any event, this setup is suboptimal; instead, we should have a single
instance of jpeg_nbits_table in some external source file, and the
header can declare it like any other variable.