Use pipe as sed regexp delimiter

Somewhat prevents regular expression turning into a 'picket fence'
Fix parsing of /proc/${pid}/maps with deleted files

When a memory-mapped file is deleted (e.g. by package update), it
becomes marked as such in maps:

00008000-003b9000 r-xp 00000000 00:0b 73450      /usr/bin/somebin (deleted)

rich-core-dumper parsed this as:

00008000 /usr/bin/somebin (deleted)

confusing gdb as a result.