gnu: Add eSpeak NG.

* gnu/packages/speech.scm (espeak-ng): New public variable.

gnu/packages/speech.scm

@@ -1,6 +1,6 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2016 David Thompson <davet@gnu.org>
-;;; Copyright © 2016 Marius Bakke <mbakke@fastmail.com>
+;;; Copyright © 2016, 2019 Marius Bakke <mbakke@fastmail.com>
 ;;; Copyright © 2017 Leo Famulari <leo@famulari.name>
 ;;; Copyright © 2018 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;; Copyright © 2016 Kei Kebreau <kkebreau@posteo.net>
@@ -32,6 +32,7 @@
   #:use-module (gnu packages compression)
   #:use-module (gnu packages gcc)
   #:use-module (gnu packages glib)
+  #:use-module (gnu packages linux)
   #:use-module (gnu packages pkg-config)
   #:use-module (gnu packages pulseaudio)
   #:use-module (gnu packages python)
@@ -90,6 +91,34 @@ at high speeds, but is not as natural or smooth as larger synthesizers which are
 based on human speech recordings.")
        (license license:gpl3+)))
 
+(define-public espeak-ng
+  (package
+    (name "espeak-ng")
+    (version "1.49.2")
+    (home-page "https://github.com/espeak-ng/espeak-ng")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append home-page "/releases/download/" version
+                                  "/espeak-ng-" version ".tar.gz"))
+              (sha256
+               (base32 "1d10x9rbvqi2zwcz65fxh04k0x0scnk7732l37laz6xra1ldhzng"))))
+    (build-system gnu-build-system)
+    (arguments
+     `(#:configure-flags '("--disable-static")
+       ;; Building in parallel triggers a race condition in 1.49.2.
+       #:parallel-build? #f
+       ;; XXX: Some tests require an audio device.
+       #:tests? #f))
+    (inputs
+     `(("libcap" ,libcap)
+       ("pcaudiolib" ,pcaudiolib)))
+    (synopsis "Software speech synthesizer")
+    (description
+     "eSpeak NG is a software speech synthesizer for more than 100 languages.
+It is based on the eSpeak engine and supports spectral and Klatt formant
+synthesis, and the ability to use MBROLA voices.")
+    (license license:gpl3+)))
+
 (define-public mitlm
   (package
     (name "mitlm")