add consts where appropriate in fs/nls/*

Add const modifiers to a few struct nls_table's member pointers in
include/linux/nls.h and adds a lot of const's in fs/nls/*.c files.

Resulting changes as visible by size:

   text    data     bss     dec     hex filename
 113612  481216    2368  597196   91ccc nls.org/built-in.o
 593548    3296     288  597132   91c8c nls/built-in.o

Apparently compiler managed to optimize code a bit better
because of const-ness.

No other changes are made.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nls/nls_euc-jp.c b/fs/nls/nls_euc-jp.c
index 7329351..7424929 100644
--- a/fs/nls/nls_euc-jp.c
+++ b/fs/nls/nls_euc-jp.c
@@ -57,7 +57,7 @@
 } while(0)
 
 /* SJIS IBM extended characters to EUC map */
-static unsigned char sjisibm2euc_map[][2] = {
+static const unsigned char sjisibm2euc_map[][2] = {
 	{0xF3, 0xF3}, {0xF3, 0xF4}, {0xF3, 0xF5}, {0xF3, 0xF6}, {0xF3, 0xF7},
 	{0xF3, 0xF8}, {0xF3, 0xF9}, {0xF3, 0xFA}, {0xF3, 0xFB}, {0xF3, 0xFC},
 	{0xF3, 0xFD}, {0xF3, 0xFE}, {0xF4, 0xA1}, {0xF4, 0xA2}, {0xF4, 0xA3},
@@ -243,7 +243,7 @@
 };
 
 /* EUC to SJIS IBM extended characters map (G3 Upper block) */
-static unsigned char euc2sjisibm_g3upper_map[][2] = {
+static const unsigned char euc2sjisibm_g3upper_map[][2] = {
 	{0xFA, 0x40}, {0xFA, 0x41}, {0xFA, 0x42}, {0xFA, 0x43}, {0xFA, 0x44},
 	{0xFA, 0x45}, {0xFA, 0x46}, {0xFA, 0x47}, {0xFA, 0x48}, {0xFA, 0x49},
 	{0xFA, 0x4A}, {0xFA, 0x4B}, {0xFA, 0x4C}, {0xFA, 0x4D}, {0xFA, 0x4E},