Revert "Revert "Revert "[ruby/fiddle] Use ffi_closure_free by default. (#20)"""

This reverts commit 87f6154bb4c67ca77ee353bb1fe25a922036c0e5.

It turned out that the change fails to build on macOS

https://rubyci.org/logs/rubyci.s3.amazonaws.com/osx1014/ruby-master/log/20200304T074503Z.fail.html.gz
```
+ make 'TESTS=--hide-skip -v fiddle' RUBYOPT=-w test-all
dyld: lazy symbol binding failed: Symbol not found: _ffi_closure_alloc
  Referenced from: /Users/hsbt/Documents/cb/tmp/build/20200304T074503Z/ruby/.ext/x86_64-darwin18/fiddle.bundle
  Expected in: flat namespace

dyld: Symbol not found: _ffi_closure_alloc
  Referenced from: /Users/hsbt/Documents/cb/tmp/build/20200304T074503Z/ruby/.ext/x86_64-darwin18/fiddle.bundle
  Expected in: flat namespace

make: *** [yes-test-all] Abort trap: 6
```

1 files changed, 14 insertions, 6 deletions

diff --git a/ext/fiddle/extconf.rb b/ext/fiddle/extconf.rb
index 5525b2c808..fce0cb4079 100644
--- a/ext/fiddle/extconf.rb
+++ b/ext/fiddle/extconf.rb
@@ -7,7 +7,8 @@ bundle = enable_config('bundled-libffi')
 if ! bundle
   dir_config 'libffi'
 
-  pkg_config("libffi")
+  pkg_config("libffi") and
+    ver = pkg_config("libffi", "modversion")
 
   if have_header(ffi_header = 'ffi.h')
     true
@@ -27,20 +28,20 @@ begin
     Dir.glob("#{$srcdir}/libffi-*/").each{|dir| FileUtils.rm_rf(dir)}
     extlibs.run(["--cache=#{cache_dir}", ext_dir])
   end
-  libffi_dir = bundle != false &&
+  ver = bundle != false &&
         Dir.glob("#{$srcdir}/libffi-*/")
         .map {|n| File.basename(n)}
         .max_by {|n| n.scan(/\d+/).map(&:to_i)}
-  unless libffi_dir
+  unless ver
     raise "missing libffi. Please install libffi."
   end
 
-  srcdir = "#{$srcdir}/#{libffi_dir}"
+  srcdir = "#{$srcdir}/#{ver}"
   ffi_header = 'ffi.h'
   libffi = Struct.new(*%I[dir srcdir builddir include lib a cflags ldflags opt arch]).new
-  libffi.dir = libffi_dir
+  libffi.dir = ver
   if $srcdir == "."
-    libffi.builddir = "#{libffi_dir}/#{RUBY_PLATFORM}"
+    libffi.builddir = "#{ver}/#{RUBY_PLATFORM}"
     libffi.srcdir = "."
   else
     libffi.builddir = libffi.dir
@@ -51,6 +52,7 @@ begin
   libffi.a = "#{libffi.lib}/libffi_convenience.#{$LIBEXT}"
   nowarn = CONFIG.merge("warnflags"=>"")
   libffi.cflags = RbConfig.expand("$(CFLAGS)".dup, nowarn)
+  ver = ver[/libffi-(.*)/, 1]
 
   FileUtils.mkdir_p(libffi.dir)
   libffi.opt = CONFIG['configure_args'][/'(-C)'/, 1]
@@ -110,6 +112,12 @@ begin
   $INCFLAGS << " -I" << libffi.include
 end
 
+if ver
+  ver = ver.gsub(/-rc\d+/, '') # If ver contains rc version, just ignored.
+  ver = (ver.split('.') + [0,0])[0,3]
+  $defs.push(%{-DRUBY_LIBFFI_MODVERSION=#{ '%d%03d%03d' % ver }})
+end
+
 have_header 'sys/mman.h'
 
 if have_header "dlfcn.h"