msgfilter: Pass previous msgid to the child process

Suggested by Pavel Kharitonov in:
<http://lists.gnu.org/archive/html/bug-gettext/2014-05/msg00022.html>.
* msgfilter.c (process_message): Set MSGFILTER_PREV_* envvar.
msgexec: Pass previous msgid to the child process

Suggested by Pavel Kharitonov in:
<http://lists.gnu.org/archive/html/bug-gettext/2014-05/msg00022.html>.
* msgexec.c (process_string): Set MSGEXEC_PREV_* envvar.
doc: Update from ISO languages database

* ISO_639: Remove Moldavian. Update Bihari, Bengali, Catalan,
Church Slavic, Divehi, Dzongkha, Ewe, Greek, Spanish, Fijian,
Gaelic, Hebrew, Interlingua, Indonesian, Inupiak, Central Khmer,
Kirghiz, Luxembourgish, Limburgan, Lao, Latvian, Norwegian Bokmal,
North Ndebele, Dutch, Norwegian Nynorsk, South Ndebele, Occitan,
Oromo, Pushto, Rundi, Romanian, Sango, Swati, South Sotho, Tswana,
Tonga, Uighur, Volapuk, Yiddish, and Zhuang.
build: Fix make distcheck

* gettext-runtime/man/Makefile.am (EXTRA_DIST): Add $(man_HTML3) so not to
regenerate them on make distcheck.
build: Handle 'environ' global variable differently on cygwin x86_64

Problem reported by Vasyl Khalak in:
<https://cygwin.com/ml/cygwin/2013-06/msg00228.html>.
* lib/execute.c.diff: New file.
* lib/spawn-pipe.c.diff: Likewise.
* Makefile.am (EXTRA_DIST): Add new patches.
Prepare for 0.19.
Regenerate files for 0.19
Release 0.19
po: Sync gettext-tools/po/Makevars with gettext-runtime/po/Makevars

* Makevars (PACKAGE_GNU, PO_DEPENDS_ON_POT)
(DIST_DEPENDS_ON_UPDATE_PO): New variables.
* Makevars.template (PACKAGE_GNU, PO_DEPENDS_ON_POT)
(DIST_DEPENDS_ON_UPDATE_PO): New variables.
msgl-check: Treat missing header errors as warnings

Problem reported by Richard Hughes at
<https://lists.fedoraproject.org/pipermail/devel/2014-June/199539.html>.
After <https://savannah.gnu.org/bugs/?40262>, "msgfmt -c" reports
error on missing PO headers.  However, it turned out to be too strict
for the projects using Launchpad Translations.  Let's relax the check
for the moment and wait for one or two release cycles.
* gettext-tools/src/msgl-check.c (check_header_entry): Report missing
required headers as warning, instead of error.
vala: Don't elide comments while parsing string literal

* x-vala.c (phase3_get): Use phase1_getc to read characters inside
a string literal.
build: Handle 'environ' global variable differently on cygwin x86_64

Amendment to commit c97dafde.
* tests/test-environ.c.diff: New file.
* Makefile.am (EXTRA_DIST): Add new patch.
Fix the last commit
tests: Ignore the LINGUAS envvar in msgfmt-desktop-2

Reported by Lars Wendler at:
<http://lists.gnu.org/archive/html/bug-gettext/2014-06/msg00002.html>.
* msgfmt-desktop-2: Unset the LINGUAS envvar.
desktop: Read LINGUAS file even if LINGUAS envvar is set

* msgfmt.c (get_languages): If the LINGUAS envvar is set, use it
to restrict the languages list read from the LINGUAS file, not to
extend the list.
(add_languages): Take an optional DESIRED_LANGUAGES argument.
desktop: Use logical filename as msgid location

* read-desktop.c (desktop_parse): Pass logical filename instead of
real filename to desktop_reader_handle_pair.
maint: Mention how to use the included gettext-tools to regeneate files
NEWS: Mention 0.19.1 changes
examples: Don't require msgfmt when compiling hello-c-gnome3

* hello-c-gnome3/Makefile.am (CLEANFILES): Clean hello.desktop.
(EXTRA_DIST): Add hello.desktop.in.
(MAINTAINERCLEANFILES): Add hello.desktop.in.
(hello.desktop): Move msgfmt invocation to...
(hello.desktop.in): ...here.