module/*.ko: prune .data, global .rodata

Evaluated every variable that lives in .data (and globals in .rodata)
in the kernel modules, and constified/eliminated/localised them
appropriately. This means that all read-only data is now actually
read-only data, and, if possible, at file scope. A lot of previously-
global-symbols became inlinable (and inlined!) constants. Probably
not in a big Wowee Performance Moment, but hey.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12899

module/avl/avl.c

@@ -119,7 +119,7 @@
  * additional memory reference. Since the translation arrays are both very
  * small the data should remain efficiently in cache.
  */
-static const int  avl_child2balance[2]	= {-1, 1};
+static const int  avl_child2balance[]	= {-1, 1};
 static const int  avl_balance2child[]	= {0, 0, 1};