(Proof of Concept) mruby tuning profiles [ci skip]

Not only mruby, it is one of the difficult things to adjust the performance vs. memory efficiency of the software.
If the approximate target device is divided and the adjustment value for it is prepared by default, it is a good indicator to do fine adjustment.

This PR divides into four profiles.

***Caution: There is no basis for the definitions in the patch.***

- `MRB_CONSTRAINED_BASELINE_PROFILE` - for microprocessors. Reduce memory consumption.
- `MRB_BASELINE_PROFILE` - Default value of mruby.
- `MRB_MAIN_PROFILE` - For desktop computers. Assume that a huge amount of RAM, 10 MiB or more, is on board.
- `MRB_HIGH_PROFILE` - for servers. Assume that mruby VM has a long life.

As you can see the profile name has been ~~stolen~~ imitated from H.264.

include/mrbconf.h

@@ -159,4 +159,70 @@
 # define TRUE 1
 #endif
 
+/*
+** mruby tuning profiles
+**/
+
+/* A profile for micro controllers */
+#if defined(MRB_CONSTRAINED_BASELINE_PROFILE)
+# ifndef KHASH_DEFAULT_SIZE
+#  define KHASH_DEFAULT_SIZE 16
+# endif
+
+# ifndef MRB_STR_BUF_MIN_SIZE
+#  define MRB_STR_BUF_MIN_SIZE 32
+# endif
+
+# ifndef MRB_HEAP_PAGE_SIZE
+#  define MRB_HEAP_PAGE_SIZE 256
+# endif
+
+/* A profile for default mruby */
+#elif defined(MRB_BASELINE_PROFILE)
+
+/* A profile for desktop computers or workstations; rich memory! */
+#elif defined(MRB_MAIN_PROFILE)
+# ifndef MRB_METHOD_CACHE
+#  define MRB_METHOD_CACHE
+# endif
+
+# ifndef MRB_METHOD_CACHE_SIZE
+#  define MRB_METHOD_CACHE_SIZE (1<<10)
+# endif
+
+# ifndef MRB_METHOD_TABLE_INLINE
+#  define MRB_METHOD_TABLE_INLINE
+# 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
+
+/* A profile for server; mruby vm is long life */
+#elif defined(MRB_HIGH_PROFILE)
+# ifndef MRB_METHOD_CACHE
+#  define MRB_METHOD_CACHE
+# endif
+
+# ifndef MRB_METHOD_CACHE_SIZE
+#  define MRB_METHOD_CACHE_SIZE (1<<12)
+# endif
+
+# ifndef MRB_METHOD_TABLE_INLINE
+#  define MRB_METHOD_TABLE_INLINE
+# 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
+#endif
+
 #endif  /* MRUBYCONF_H */