Port TZ settings to POSIX

* lisp/Makefile.in (.el.elc):
* lisp/net/tramp-sh.el (tramp-sh-handle-set-file-times):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-handle-set-file-times):
Use the POSIX standard TZ=UTC0 rather than the GNU extension
TZ=UTC to set the time zone to UTC.

lisp/Makefile.in

@@ -315,7 +315,7 @@ ifeq ($(ANCIENT),yes)
 .el.elc:
 	$(AM_V_ELC)$(emacs) $(BYTE_COMPILE_FLAGS) \
 	-l comp -f batch-byte-compile $<
-	TZ=UTC touch -t 197001010000 $@
+	TZ=UTC0 touch -t 197001010000 $@
 else
 .el.elc:
 	$(AM_V_ELC)$(emacs) $(BYTE_COMPILE_FLAGS) \

lisp/net/tramp-sh.el

@@ -1528,7 +1528,7 @@ of."
 	       time)))
 	(tramp-send-command-and-check
 	 v (format
-	    "env TZ=UTC %s %s %s %s"
+	    "env TZ=UTC0 %s %s %s %s"
 	    (tramp-get-remote-touch v)
 	    (if (tramp-get-connection-property v "touch-t")
 		(format "-t %s" (format-time-string "%Y%m%d%H%M.%S" time t))

lisp/net/tramp-sudoedit.el

@@ -568,7 +568,7 @@ the result will be a local, non-Tramp, file name."
 	       nil
 	     time)))
       (tramp-sudoedit-send-command
-       v "env" "TZ=UTC" "touch" "-t"
+       v "env" "TZ=UTC0" "touch" "-t"
        (format-time-string "%Y%m%d%H%M.%S" time t)
        (if (eq flag 'nofollow) "-h" "")
        (tramp-compat-file-name-unquote localname)))))