editors/linux-r7-office: Assorted fixes.

• Fix paths in .desktop file.
• Install icon file.
• Override LC_CTYPE with ru_RU.UTF-8 value [*].

• linux_base-c7 doesn't have C nor C.UTF-8 locales. This makes R7 Office

render gibberish in file names in the "Open File ..." dialog. The LC_CTYPE
override to ru_RU.UTF-8 makes most sense - the userbase of this suite is likely
to consist of Russian-speaking users. Oterwise the user always may set LC_ALL to
something else to switch R7 Office to the different locale.

Reported by: fluffy
Sponsored by: Serenity Cybersecurity, LLC