app-text/pdfpc: Fix dep on pkg-config
sys-fs/{fuse-exfat,exfat-utils}: Comment suggestions

Reported by zlin
dev-lang/ott: Comment suggestion

Reported by zlin
dev-lang/ocaml: Sorting options

Reported by zlin
dev-lang/coq: Minor exlib simplification.

Reported by zlin
dev-lang/ott: Quote

Reported by zlin