WL#5303: Romansh locale for DAYNAME, MONTHNAME, DATE_FORMAT

If @@lc_time_names='rm_CH', DAYNAME() and MONTHNAME() and
DATE_FORMAT() functions should produce appropriate Romansh
results for day abbreviation, day, hours am/pm,
month abbreviations, and months.

Apply the contributed patches as explained in
BUG#50915 "Romansh language patch for MySQL server".

Functions DAYNAME, MONTHNAME, DATE_FORMAT currently do not support
Romansh locale.

This task will add rm_CH locale with appropriate month/day names.

Days
----

day abbreviation: (abday):

Sunday    = "du"
Monday    = "gli"
Tuesday   = "ma"
Wednesday = "me"
Thursday  = "gie"
Friday    = "ve"
Saturday  = "so"

day:

Sunday    = "dumengia"
Monday    = "glindesdi"
Tuesday   = "mardi"
Wednesday = "mesemna"
Thursday  = "gievgia"
Friday    = "venderdi"
Saturday  = "sonda"

Hours
-----

am= "AM"
pm= "PM"

Months
------

month abbreviation: (abmon):
Jan = "schan"
Feb = "favr"
Mar = "mars"
Apr = "avr"
May = "matg"
Jun = "zercl"
Jul = "fan"
Aug = "avust"
Sep = "sett"
Oct = "oct"
Nov = "nov"
Dec = "dec"

month: (mon):
January   = "schaner"
February  = "favrer"
March     = "mars"
April     = "avrigl"
May       = "matg"
June      = "zercladur"
July      = "fanadur"
August    = "avust"
September = "settember"
October   = "october"
November  = "november"
December  = "december"

Unaffected locale uses
----------------------

For "FORMAT(X,D[,locale])", which is not a linguistic issue,
'rm_CH' should produce the same format as 'de_CH'.

For lc_messages='rm_CH', use the English messages.

Authority
---------

The month and day names are what one would expect for Romansh (Grischun).

From a comment on BUG#50915 by Beat Vontobel, who supplied a patch:
"
Peter, the short answer is: Yes, the abbreviations used in this patch are
those suggested by the "Pledari Grond" for "Rumantsch Grischun", as
maintained by the "Lia Rumantscha" (http://www.liarumantscha.ch/).
"Rumantsch Grischun" is what's now officially used on the
national and state (Canton of Graubuenden) level in writing.
The vocabulary can be accessed online at http://www.pledarigrond.ch/ - enter
the full German or Romansh words for month/weekday names and you'll also
get the Romansh abbreviations for your own verification.
"
This has been confirmed.

References
----------

BUG#50915 Romansh language patch for MySQL server (feature request)