target-xtensa: mark XtensaConfig structs as unused

The XtensaConfig structs will be defined but not used if they are
for the opposite endianness from that of the binary being built;
keep the compiler from complaining about this by marking them
with the 'unused' attribute.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Acked-by: NMax Filippov <jcmvbkbc@gmail.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

target-xtensa/core-dc232b.c

@@ -33,7 +33,7 @@
 #include "core-dc232b/core-isa.h"
 #include "overlay_tool.h"
 
-static const XtensaConfig dc232b = {
+static const XtensaConfig dc232b __attribute__((unused)) = {
     .name = "dc232b",
     .gdb_regmap = {
         .num_regs = 120,

target-xtensa/core-dc233c.c

@@ -34,7 +34,7 @@
 #include "core-dc233c/core-isa.h"
 #include "overlay_tool.h"
 
-static const XtensaConfig dc233c = {
+static const XtensaConfig dc233c __attribute__((unused)) = {
     .name = "dc233c",
     .gdb_regmap = {
         .num_regs = 121,

target-xtensa/core-fsf.c

@@ -33,7 +33,7 @@
 #include "core-fsf/core-isa.h"
 #include "overlay_tool.h"
 
-static const XtensaConfig fsf = {
+static const XtensaConfig fsf __attribute__((unused)) = {
     .name = "fsf",
     /* GDB for this core is not supported currently */
     .clock_freq_khz = 10000,