patch 9.0.2130: some errors with translation Makefiles

patch 9.0.2130: some errors with translation Makefiles

Problem:  some errors with translation Makefiles
Solution: fix issues

Update src/po/ makefiles after 9.0.2127

* Change how to check `%LANGUAGE%`.
  Check it only when needed.
* Add double quotes to where `GETTEXT_PATH` is used.
  Before 9.0.2127, this worked: `nmake -f Make_mvc.mak GETTEXT_PATH="\"C:\Program Files\Git\usr\bin\""` (which was a bit tricky.)
  9.0.2127 broke this and syntax error occurred.
  This doesn't work either in 9.0.2127: `nmake -f Make_mvc.mak GETTEXT_PATH="C:\Program Files\Git\usr\bin"`
  With this Commit, this works: `nmake -f Make_mvc.mak GETTEXT_PATH="C:\Program Files\Git\usr\bin"`
* Better error report for the `check` target.
  Show the line number of the error. (Imported from vim-jp/lang-ja.)

closes: #13567

Signed-off-by: Ken Takata <kentkt@csc.jp>
Signed-off-by: Christian Brabandt <cb@256bit.org>