fix(temp): rake-compiler explicitly builds miniruby first

See ruby/ruby@50d81bf for the upstream
change that uses miniruby to resolve symbols.

This should either be fixed upstream in rake-compiler or in Ruby's
build system, not sure which.

build/patches2/rake-compiler-1.1.6/0005-make-miniruby.patch

@@ -0,0 +1,12 @@
+diff --git a/tasks/bin/cross-ruby.rake b/tasks/bin/cross-ruby.rake
+index 8317a2a..d9bfe4c 100644
+--- a/tasks/bin/cross-ruby.rake
++++ b/tasks/bin/cross-ruby.rake
+@@ -129,6 +129,7 @@
+
+     # make
+     file "#{build_dir}/ruby.exe" => ["#{build_dir}/Makefile"] do |t|
++      sh "#{MAKE} miniruby", chdir: File.dirname(t.prerequisites.first)
+       sh MAKE, chdir: File.dirname(t.prerequisites.first)
+     end
+