* lib/mkmf.rb (pkg_config): Add optional argument "option".
  If it is given, it returns the result of
  `pkg-config --<option> <pkgname>`.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40218 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* ext/fiddle/extconf.rb: define RUBY_LIBFFI_MODVERSION macro.

* ext/fiddle/closure.c (USE_FFI_CLOSURE_ALLOC): define 0 or 1
  with platform and libffi's version. [Bug #3371]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40219 b2dd03c8-39d4-4d8f-98ff-823fe69b080e