Remove no longer used `MRB_IV_SEGMENT_SIZE; close #5188 [ci skip]

doc/guides/mrbconf.md

@@ -123,11 +123,6 @@ largest value of required alignment.
 * If defined represent `mrb_value` as a word.
 * If defined `Float` will be a mruby object with `RBasic`.
 
-## Instance variable configuration.
-`MRB_IV_SEGMENT_SIZE`
-* Default value is `4`.
-* Specifies size of each segment in segment list.
-
 ## Reduce heap memory configuration.
 
 `MRB_USE_LINK_TIME_RO_DATA_P`

include/mrbconf.h

@@ -213,10 +213,6 @@
 #  define MRB_METHOD_CACHE_SIZE (1<<10)
 # endif
 
-# ifndef MRB_IV_SEGMENT_SIZE
-#  define MRB_IV_SEGMENT_SIZE 32
-# endif
-
 # ifndef MRB_HEAP_PAGE_SIZE
 #  define MRB_HEAP_PAGE_SIZE 4096
 # endif
@@ -227,10 +223,6 @@
 #  define MRB_METHOD_CACHE_SIZE (1<<12)
 # endif
 
-# ifndef MRB_IV_SEGMENT_SIZE
-#  define MRB_IV_SEGMENT_SIZE 64
-# endif
-
 # ifndef MRB_HEAP_PAGE_SIZE
 #  define MRB_HEAP_PAGE_SIZE 4096
 # endif