🔒 Fix missing HTTPS on links

doc/guides/gc-arena-howto.md

@@ -3,7 +3,7 @@
 _This is an English translation of [Matz's blog post][matz blog post]
 written in Japanese._
 _Some parts are updated to reflect recent changes._
-[matz blog post]: http://www.rubyist.net/~matz/20130731.html
+[matz blog post]: https://www.rubyist.net/~matz/20130731.html
 
 When you are extending mruby using C language, you may encounter
 mysterious "arena overflow error" or memory leak or very slow

include/mruby.h

@@ -22,7 +22,7 @@
 ** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 ** SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 **
-** [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
+** [ MIT license: https://www.opensource.org/licenses/mit-license.php ]
 */
 
 /**

mrbgems/mruby-io/README.md

@@ -13,7 +13,7 @@ Add the line below to your build configuration.
 ## Implemented methods
 
 ### IO
- - http://doc.ruby-lang.org/ja/1.9.3/class/IO.html
+ - https://doc.ruby-lang.org/ja/1.9.3/class/IO.html
 
 | method                     | mruby-io | memo |
 | -------------------------  | -------- | ---- |
@@ -97,7 +97,7 @@ Add the line below to your build configuration.
 | IO#write_nonblock          |          |      |
 
 ### File
- - http://doc.ruby-lang.org/ja/1.9.3/class/File.html
+ - https://doc.ruby-lang.org/ja/1.9.3/class/File.html
 
 | method                      | mruby-io | memo |
 | --------------------------- | -------- | ---- |

mrbgems/mruby-sleep/README.md

@@ -23,6 +23,6 @@ usleep(10000)
 # License
 under the MIT License:
 
-* http://www.opensource.org/licenses/mit-license.php
+* https://www.opensource.org/licenses/mit-license.php
 
 

mrbgems/mruby-sleep/src/mrb_sleep.c

@@ -23,7 +23,7 @@
 ** TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 ** SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 **
-** [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
+** [ MIT license: https://www.opensource.org/licenses/mit-license.php ]
 */
 
 #include <time.h>