Enable NLS catalog of csh(1).

The tcsh 6.14 uses libiconv to convert catalogs to appropriate charset
dynamically.  However, we don't have libiconv in our tree.  So, I made
some hack to load libiconv dynamically.  If libiconv is available, you
can use catalogs for more locales than the locales which catalog is
actually installed.
To use this feature, you need to symlink catalogs to appropriate
locales.  You can do this by installing ports/shells/tcsh_nls.

Reviewed by:	arch (no objection)
MFC after:	1 week

bin/csh/Makefile

@@ -70,12 +70,30 @@ NLSLINKS_de_DE.ISO8859-1= de_AT.ISO8859-1 de_AT.ISO8859-15 de_CH.ISO8859-1 \
 NLSLINKS_it_IT.ISO8859-1= it_CH.ISO8859-1 it_CH.ISO8859-15 it_IT.ISO8859-15
 NLSLINKS_es_ES.ISO8859-1= es_ES.ISO8859-15
 
+.if defined(NO_NLS_CATALOGS) || defined(RESCUE)
+CFLAGS+= -DNO_NLS_CATALOGS
+.else
+CFLAGS+= -DHAVE_ICONV
+SRCS+=	iconv_stub.c
+# Folloing links can be installed from ports/shells/tcsh_nls:
+# NLSLINKS_de_DE.ISO8859-1 += de_AT.UTF-8 de_CH.UTF-8 de_DE.UTF-8
+# NLSLINKS_el_GR.ISO8859-7 = el_GR.UTF-8
+# NLSLINKS_es_ES.ISO8859-1 += es_ES.UTF-8
+# NLSLINKS_et_EE.ISO8859-15 = et_EE.UTF-8
+# NLSLINKS_fi_FI.ISO8859-1 += fi_FI.UTF-8
+# NLSLINKS_fr_FR.ISO8859-1 += fr_BE.UTF-8 fr_CA.UTF-8 fr_CH.UTF-8 fr_FR.UTF-8
+# NLSLINKS_it_IT.ISO8859-1 += it_CH.UTF-8 it_IT.UTF-8
+# NLSLINKS_ja_JP.eucJP = ja_JP.SJIS ja_JP.UTF-8
+# NLSLINKS_ru_RU.KOI8-R = ru_RU.CP1251 ru_RU.CP866 ru_RU.ISO8859-5 ru_RU.UTF-8
+# NLSLINKS_uk_UA.KOI8-U = uk_UA.ISO8859-5 uk_UA.UTF-8
+.endif
+
 NLSNAME= tcsh
 
 .for catalog in ${CATALOGS}
 NLS+=		${catalog:C/.*://}
 NLSSRCDIR_${catalog:C/.*://}= ${TCSHDIR}/nls/${catalog:C/:.*//}
-NLSSRCFILES_${catalog:C/.*://}!= cd ${NLSSRCDIR_${catalog:C/.*://}}; echo set[0-9]*
+NLSSRCFILES_${catalog:C/.*://}!= cd ${NLSSRCDIR_${catalog:C/.*://}}; echo charset set[0-9]*
 .endfor
 
 csh.1: tcsh.man