Refine `preprocess_options`; ref d95ffb03

If we modify an option that may have been specified by users, we may
make unintended changes, so it is better not to modify it as much as
possible, IMO.

It's for internal use. Please use `conf.disable_presym`.

Split `presym_table` for reduced program size

Because a structure that is an element of `presym_table` has padding, split
it into individual arrays for name and length.

#### Result (64-bit CPU with full-core gembox)

|        |   mruby    | libmruby.a |
|--------|------------|------------|
| Before | 1,087,444B | 1,476,872B |
| After  | 1,079,340B | 1,469,784B |

Rename `.i` created for presym scan to `.pi`

This is because compiler's `-save-temps=obj` option creates `.i` with the
same name.

Fix typos in `mruby/presym/{disable,enable}.h` [ci skip]

Avoid 'possible loss of data' casting in binary search

Fix "Use `MRB_SYM()` for error class retrieval"; ref 2ddfd50d

Because it may not be expected result.
example: https://wandbox.org/permlink/F5Mp7IEJ1VY3CFLp

The new macro (`MRB_E_SYM`) was not being used, so it is being used. Also
`MRB_E_SYM` is confusing with `MRB_SYM_E`, so change it to `MRB_ERROR_SYM`.

This reverts commit 34f82f24.
Ref #5282

To describe how to use symbols, especially preallocated symbols from C.

Or no argument at all.

Where `mruby-config` command should be generated.

Note that `MRB_SYM()` is only available when `mruby/presym.h` is
included. Use `mrb_intern_lit()` otherwise.

This reverts commit dc51d89a.

Fix TYPO and checking minor version in RITE BINARY HEADER

For easier compiling and linking of the application embedding `mruby`