make[2]: Entering directory '/opt/mmmv/ruby/src/tmp/ruby-2.3.0/ext/tk/tkutil'
make[2]: Nothing to be done for 'static'.
make[2]: Leaving directory '/opt/mmmv/ruby/src/tmp/ruby-2.3.0/ext/tk/tkutil'
make[2]: Entering directory '/opt/mmmv/ruby/src/tmp/ruby-2.3.0'
generating enc.mk
compiling enc/encinit.c
linking shared-library libruby.so.2.3.0
linking ruby
make[2]: Leaving directory '/opt/mmmv/ruby/src/tmp/ruby-2.3.0'
make[1]: Leaving directory '/opt/mmmv/ruby/src/tmp/ruby-2.3.0'
Generating RDoc documentation
/opt/mmmv/ruby/src/tmp/ruby-2.3.0/lib/time.rb:3:in `require': cannot load such file -- date (LoadError)
	from /opt/mmmv/ruby/src/tmp/ruby-2.3.0/lib/time.rb:3:in `<top (required)>'
	from /opt/mmmv/ruby/src/tmp/ruby-2.3.0/lib/rdoc/rdoc.rb:7:in `require'
	from /opt/mmmv/ruby/src/tmp/ruby-2.3.0/lib/rdoc/rdoc.rb:7:in `<top (required)>'
	from ./bin/rdoc:16:in `require'
	from ./bin/rdoc:16:in `<main>'
uncommon.mk:441: recipe for target 'rdoc' failed
make: *** [rdoc] Error 1

real	6m56.743s
user	4m31.644s
sys	0m50.484s
ubuntu@uu:/opt/mmmv/ruby/src/tmp/ruby-2.3.0$ uname -a
Linux uu 4.2.0-27-generic #32-Ubuntu SMP Fri Jan 22 04:49:08 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
ubuntu@uu:/opt/mmmv/ruby/src/tmp/ruby-2.3.0$ date
Wed Feb 10 14:41:04 EET 2016
ubuntu@uu:/opt/mmmv/ruby/src/tmp/ruby-2.3.0$ echo $CFLAGS
-m64 -ftree-vectorize
ubuntu@uu:/opt/mmmv/ruby/src/tmp/ruby-2.3.0$ echo $CXXFLAGS
-m64 -ftree-vectorize
ubuntu@uu:/opt/mmmv/ruby/src/tmp/ruby-2.3.0$ echo $CC