www/mod_rpaf2: Update to 0.8.4

• Update to 0.8.4 fixing Apache 2.4 compat [1]
• Add modules.d config file [1] fixing [2]
• Add upstream fix for clang warning [1]

PR: 209869 [1], 222374 [2]
Submitted by: Geoffroy Desvernay <dgeo@centrale-marseille.fr> [1]
Reported by: mayhem30@gmail.com [2]
With hat: apache