Fix localization: Fix build: Fix dangling references.

Problem:  Makefile references some files that don't exist anymore.
Solution: Remove those references.
Fix localization: Fix build: Fix included source files.

Problem  : Previous build assumed all *.c files were in parent dir. It
           only included globals.h, too.
Solution : Include all *.c and *.h files under parent dir (including
           subdirs).
Fix localization: Fix build: Fix sed issue on OSX.

Problem:  On OSX, sed commands processing files converted to encodings
          other that UTF-8 fail with "RE error: illegal byte sequence".
Solution: Make sed execute with C locale throgh environment variables
          (LANG=C, LC_ALL=C, LC_CTYPE=C).
Fix localization: Fix build: Fix sjis-fixing executable.

Problem:  Executable used to fix japanese files with sjis encoding
          (sjiscorr) fails to compile.
Solution: - Add mising includes.
          - Remove __END_DECLS.
          - Add removed comments.
Fix localization: Fix build: Improve checking.

Problem  : Currently, 'make check' gives no explanations when it fails,
           only the name of the po file which caused the halt. Then,
           you have to manually run check.vim on that file to see what
           happened.
Solution : Generate a 'check.log' file on every execution of check.vim
           (overwriting if already existing). That way, when make halts,
           you can go there and see details about failure.
Fix localization: Fix po files.

Problem:  Build fails because of some messages being repeated.
          Curiously, all repeated messages have this comment:
          "Explicit typecast avoids warning on Mac OS X 10.6".
          No idea why.
Solution: Remove repeated messages.
Fix localization: Update po files.

Sync po files to code at 3a68a4861adcc950cdbde709d4841f8ea0c52b12.
Merge #713 'Fix localization'