Add gcc to the prequisites list

I was looking at my logs for a sanity.system test and I noticed that it used GCC. I then went to the prerequisites list and I noticed that GCC was not listed.
Can you please update the prerequisite list to indicate that GCC is required and which version is needed if applicable?
Related to eclipse/openj9#4208

Start by locating the repository's prerequisite list and compare its existing entries with the requirement described here. Update it to list GCC and specify the required version if applicable; done means the prerequisite documentation clearly includes both.

Written by the indexing model from the issue text.