Various pages: Remove explicit blank lines, replacing them with .PP when appropriate

Various pages: Remove explicit blank lines, replacing them with .PP when appropriate

Rationale:
$ man 7 man-pages 2>/dev/null | sed -n /Paragraphs/,/^$/p
       Paragraphs should be separated by suitable markers (usually
       either .PP or .IP).  Do not separate paragraphs using blank
       lines,  as  this  results  in poor rendering in some output
       formats (such as PostScript and PDF).

Fix:
$ sed -i -e '1,/^\.EX/s/^$/.PP/' -e '/^\.EE/,/^\.EX/s/^$/.PP/' man?/*

And then some manual adjustments.

Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>