Contribs: update gettext to 0.19.1

(cherry picked from commit 5624a0fcf27da305d9547db6d717b5197ef9214c)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

contrib/src/gettext/SHA512SUMS

-812074a74c946c34b97efa351a3d2b1ff5b6321714e88912d188ba70c868c9d9b7263a8507514c05c1667bc5613e88d9a44569575db73dd046780824b0975bfd  gettext-0.18.3.tar.gz
+be67f059f18babbdbb28b2087082be1e7595ecf70d8efc7468629b1b8650abc82d040ea5680596af158bd0d641255fe6930195b8a68797c42cf280b81dca072c  gettext-0.19.1.tar.gz

contrib/src/gettext/rules.mak

 # gettext
-GETTEXT_VERSION=0.18.3
+GETTEXT_VERSION=0.19.1
 GETTEXT_URL=$(GNU)/gettext/gettext-$(GETTEXT_VERSION).tar.gz
 
 PKGS += gettext