mingw: let's use gettext with MSYS2
This solves two problems:
- we now have proper localisation even on Windows
- we sidestep the infamous "BUG: your vsnprintf is broken (returned -1)"
message when running "git init" (which otherwise prevents the entire
test suite from running) because libintl.h overrides vsnprintf() with
libintl_vsnprintf() [*1*]
The latter issue is rather crucial, as *no* test passes in Git for
Windows without this fix.
Footnote *1*: gettext_git=http://git.savannah.gnu.org/cgit/gettext.git
$gettext_git/tree/gettext-runtime/intl/libgnuintl.in.h#n380
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>