feat: support compilation with TruffleRuby

[ankane]

Purpose

Hi @yoshoku, this PR fixes a compilation error with TruffleRuby.

compiling ../../../../../ext/numo/narray/narray.c
../../../../../ext/numo/narray/narray.c: In function ‘nary_copy_flags’:
../../../../../ext/numo/narray/narray.c:855:3: error: implicit declaration of function ‘RBASIC’ [-Werror=implicit-function-declaration]
  855 |   RBASIC(dst)->flags |= (RBASIC(src)->flags) & (FL_USER1 | FL_USER2 | FL_USER3 | FL_USER4 |
      |   ^~~~~~
../../../../../ext/numo/narray/narray.c:855:14: error: invalid type argument of ‘->’ (have ‘int’)
  855 |   RBASIC(dst)->flags |= (RBASIC(src)->flags) & (FL_USER1 | FL_USER2 | FL_USER3 | FL_USER4 |
      |              ^~
../../../../../ext/numo/narray/narray.c:855:37: error: invalid type argument of ‘->’ (have ‘int’)
  855 |   RBASIC(dst)->flags |= (RBASIC(src)->flags) & (FL_USER1 | FL_USER2 | FL_USER3 | FL_USER4 |

Summary of Changes

Uses RBASIC_FLAGS and RBASIC_SET_FLAGS to access flags as recommended in truffleruby/truffleruby#3751.

Testing

• Tests pass locally (with CRuby)
• Manual testing completed

There are still 16 test failures with TruffleRuby, which can hopefully be addressed in future PRs (see the discussion in truffleruby/truffleruby#3751).

Related Issues

None

[ankane]

Also fixes this error on CI.

[ankane]

Thanks @yoshoku!

[yoshoku]

@ankane Thank you for your contribution! I am not very familiar with TruffleRuby, so your help was greatly appreciated.