tcg: add "-accel tcg,tb-size" and deprecate "-tb-size"

-tb-size fits nicely in the new framework for accelerator-specific options.  It
is a very niche option, so insta-deprecate it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/sysemu/accel.h

@@ -64,8 +64,6 @@ typedef struct AccelClass {
 #define ACCEL_GET_CLASS(obj) \
     OBJECT_GET_CLASS(AccelClass, (obj), TYPE_ACCEL)
 
-extern unsigned long tcg_tb_size;
-
 AccelClass *accel_find(const char *opt_name);
 int accel_init_machine(AccelState *accel, MachineState *ms);