package/brltty: add host-gawk dependency

host-gawk is used by brltty to build brlapi_constants.h, the build will
fail if mawk is used instead of gawk

Fixes:
 - http://autobuild.buildroot.org/results/4c77f03cbc7ab9e5ae9f24fe6eead1d76c50c743

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/brltty/brltty.mk

@@ -12,7 +12,11 @@ BRLTTY_INSTALL_TARGET_OPTS = INSTALL_ROOT=$(TARGET_DIR) install
 BRLTTY_LICENSE = LGPL-2.1+
 BRLTTY_LICENSE_FILES = LICENSE-LGPL README
 
-BRLTTY_DEPENDENCIES = $(TARGET_NLS_DEPENDENCIES) host-autoconf host-pkgconf \
+BRLTTY_DEPENDENCIES = \
+	$(TARGET_NLS_DEPENDENCIES) \
+	host-autoconf \
+	host-gawk \
+	host-pkgconf \
 	$(if $(BR2_PACKAGE_AT_SPI2_CORE),at-spi2-core)
 
 BRLTTY_CONF_ENV = \