re_pattern_buffer: shrink from 464 to 448 bytes on 64-bit

* include/ruby/oniguruma.h (struct re_pattern_buffer): shrink to 448
  bytes from 464 bytes on 64-bit.  This breaks the ABI.
  [Feature #10034]

Reducing struct re_pattern_buffer from 464 to 448 bytes allows it to fit
into neatly into seven 64-byte cache lines on x86-64 systems.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46881 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* remove trailing spaces.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46882 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
rb_io_t: shrink from 216 to 200 bytes on 64-bit

* include/ruby/io.h (rb_io_t): shrink to 200 bytes from 216 on 64-bit
  This puts us within 8 bytes of being three cache lines instead of
  four lines on x86-64.  This breaks the ABI.
  [Feature #10050]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46883 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
rb_io_buffer_t: pack structure

* include/ruby/io.h (rb_io_buffer_t): pack structure
  Reduces rb_io_t from 200 to 192 bytes, allowing rb_io_t to
  occupy one less cache line.
  [Feature #10050]

n.b. this leaves a 4-byte hole after the `cbuf' field which may
be used for future expansion.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46884 b2dd03c8-39d4-4d8f-98ff-823fe69b080e