Ruby

io.c: reduce size of :wait_*able code paths

• io.c (sym_wait_readable, sym_wait_writable): declare
  (io_getpartial): use sym_wait_readable
  (io_write_nonblock): use sym_wait_writable
  (Init_IO): initialize sym_wait_*able

On 32-bit x86:

text data bss dec hex filename
121003 56 252 121311 1d9df io.o
121035 56 252 121343 1d9ff io.o.orig

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50779 b2dd03c8-39d4-4d8f-98ff-823fe69b080e