Harmonize source files coding tag to "utf-8"

Some files were tagged as "utf8" (no dash before “8"), some as "utf-8"
(dash before “8”). Since for example Emacs per default complains about
"utf8", but liking "utf-8", we harmonize all coding tags to "utf-8".

Change-Id: If1533a4d3f8427a7d235a3bb776745e444d03e06
Merge "Harmonize source files coding tag to "utf-8""