build: Read LINGUAS at 'make' time, not at 'configure' time.

build: Read LINGUAS at 'make' time, not at 'configure' time.

* gettext-runtime/m4/po.m4 (AM_PO_SUBDIRS): Move the obsolete ALL_LINGUAS check.
Define DESIRED_LINGUAS. Don't compute ALL_LINGUAS, POFILES, UPDATEPOFILES,
DUMMYPOFILES, GMOFILES, INST_LINGUAS, CATALOGS any more.
(AM_POSTPROCESS_PO_MAKEFILE): Don't compute and substitute ALL_LINGUAS, POFILES,
UPDATEPOFILES, DUMMYPOFILES, GMOFILES, PROPERTIESFILES, CLASSFILES, QMFILES,
MSGFILES, RESOURCESDLLFILES, INST_LINGUAS, CATALOGS, JAVACATALOGS, QTCATALOGS,
TCLCATALOGS, CSHARPCATALOGS any more. Don't add rules for Tcl and C# catalogs
any more.
* gettext-runtime/po/Makefile.in.in (ALL_LINGUAS, POFILES, GMOFILES,
UPDATEPOFILES, DUMMYPOFILES): Define with a computed value.
(DESIRED_LINGUAS): New macro.
(INST_LINGUAS, CATALOGS): Define with a computed value.
* gettext-tools/examples/po/Makefile.am (ALL_LINGUAS, POFILES, UPDATEPOFILES,
DUMMYPOFILES): Define with a computed value.
* gettext-tools/examples/hello-*/po/Makefile.am (ALL_LINGUAS, POFILES, GMOFILES,
UPDATEPOFILES, DUMMYPOFILES): Define with a computed value.
(DESIRED_LINGUAS): New macro.
(INST_LINGUAS, CATALOGS): Define with a computed value.
* gettext-tools/examples/hello-csharp*/po/Makefile.am (ALL_LINGUAS, POFILES,
UPDATEPOFILES, DUMMYPOFILES, RESOURCESDLLFILES): Define with a computed value.
Include .csharp-rules.
(DESIRED_LINGUAS): New macro.
(INST_LINGUAS, CATALOGS): Define with a computed value.
(DISTCLEANFILES): New variable.
* gettext-tools/examples/hello-tcl*/po/Makefile.am (ALL_LINGUAS, POFILES,
UPDATEPOFILES, DUMMYPOFILES, MSGFILES): Define with a computed value.
Include .tcl-rules.
(DESIRED_LINGUAS): New macro.
(INST_LINGUAS, CATALOGS): Define with a computed value.
(DISTCLEANFILES): New variable.