patch 8.0.0420: text garbled when the system encoding differs from 'encoding'

Problem:    When running :make the output may be in the system encoding,
            different from 'encoding'.
Solution:   Add the 'makeencoding' option. (Ken Takata)

runtime/doc/options.txt

@@ -4994,6 +4994,25 @@ A jump table for the options with a short description can be found at |Q_op|.
 	This option cannot be set from a |modeline| or in the |sandbox|, for
 	security reasons.
 
+					*'makeencoding'* *'menc'*
+'makeencoding' 'menc'	string	(default "")
+			global or local to buffer |global-local|
+			{only available when compiled with the |+multi_byte|
+			feature}
+			{not in Vi}
+	Encoding used for reading the output of external commands.  When empty,
+	encoding is not converted.
+	This is used for `:make`, `:lmake`, `:grep`, `:lgrep`, `:grepadd`,
+	`:lgrepadd`, `:cfile`, `:cgetfile`, `:caddfile`, `:lfile`, `:lgetfile`,
+	and `:laddfile`.
+
+	This would be mostly useful when you use MS-Windows and set 'encoding'
+	to "utf-8".  If |+iconv| is enabled and GNU libiconv is used, setting
+	'makeencoding' to "char" has the same effect as setting to the system
+	locale encoding.  Example: >
+		:set encoding=utf-8
+		:set makeencoding=char	" system locale is used
+<
 						*'makeprg'* *'mp'*
 'makeprg' 'mp'		string	(default "make", VMS: "MMS")
 			global or local to buffer |global-local|

runtime/doc/quickfix.txt

@@ -164,6 +164,9 @@ processing a quickfix or location list command, it will be aborted.
 			keep Vim running while compiling.  If you give the
 			name of the errorfile, the 'errorfile' option will
 			be set to [errorfile].  See |:cc| for [!].
+			If the encoding of the error file differs from the
+			'encoding' option, you can use the 'makeencoding'
+			option to specify the encoding.
 
 							*:lf* *:lfile*
 :lf[ile][!] [errorfile]	Same as ":cfile", except the location list for the
@@ -175,6 +178,9 @@ processing a quickfix or location list command, it will be aborted.
 :cg[etfile] [errorfile]					*:cg* *:cgetfile*
 			Read the error file.  Just like ":cfile" but don't
 			jump to the first error.
+			If the encoding of the error file differs from the
+			'encoding' option, you can use the 'makeencoding'
+			option to specify the encoding.
 
 
 :lg[etfile] [errorfile]					*:lg* *:lgetfile*
@@ -185,6 +191,9 @@ processing a quickfix or location list command, it will be aborted.
 :caddf[ile] [errorfile]	Read the error file and add the errors from the
 			errorfile to the current quickfix list. If a quickfix
 			list is not present, then a new list is created.
+			If the encoding of the error file differs from the
+			'encoding' option, you can use the 'makeencoding'
+			option to specify the encoding.
 
 							*:laddf* *:laddfile*
 :laddf[ile] [errorfile]	Same as ":caddfile", except the location list for the
@@ -320,6 +329,7 @@ use this code: >
 	endfunction
 
 	au QuickfixCmdPost make call QfMakeConv()
+Another option is using 'makeencoding'.
 
 
 EXECUTE A COMMAND IN ALL THE BUFFERS IN QUICKFIX OR LOCATION LIST:
@@ -586,6 +596,9 @@ lists, use ":cnewer 99" first.
 			   like |:cnext| and |:cprevious|, see above.
 			This command does not accept a comment, any "
 			characters are considered part of the arguments.
+			If the encoding of the program output differs from the
+			'encoding' option, you can use the 'makeencoding'
+			option to specify the encoding.
 
 							*:lmak* *:lmake*
 :lmak[e][!] [arguments]
@@ -645,6 +658,7 @@ read the error messages: >
 	au QuickfixCmdPost make call QfMakeConv()
 
 (Example by Faque Cheng)
+Another option is using 'makeencoding'.
 
 ==============================================================================
 5. Using :vimgrep and :grep				*grep* *lid*
@@ -759,6 +773,9 @@ id-utils) in a similar way to its compiler integration (see |:make| above).
 			When 'grepprg' is "internal" this works like
 			|:vimgrep|.  Note that the pattern needs to be
 			enclosed in separator characters then.
+			If the encoding of the program output differs from the
+			'encoding' option, you can use the 'makeencoding'
+			option to specify the encoding.
 
 							    *:lgr* *:lgrep*
 :lgr[ep][!] [arguments]	Same as ":grep", except the location list for the
@@ -783,6 +800,10 @@ id-utils) in a similar way to its compiler integration (see |:make| above).
 				  \ | catch /E480:/
 				  \ | endtry"
 <
+			If the encoding of the program output differs from the
+			'encoding' option, you can use the 'makeencoding'
+			option to specify the encoding.
+
 							*:lgrepa* *:lgrepadd*
 :lgrepa[dd][!] [arguments]
 			Same as ":grepadd", except the location list for the

runtime/doc/quickref.txt

@@ -782,6 +782,7 @@ Short explanation of each option:		*option-list*
 'macatsui'		    Mac GUI: use ATSUI text drawing
 'magic'			    changes special characters in search patterns
 'makeef'	  'mef'     name of the errorfile for ":make"
+'makeencoding'	  'menc'    encoding of external make/grep commands
 'makeprg'	  'mp'	    program to use for the ":make" command
 'matchpairs'	  'mps'     pairs of characters that "%" can match
 'matchtime'	  'mat'     tenths of a second to show matching paren