uemacs: fix package source

There is no bz2 archive for uemacs on kernel.org, only a gz archive.

Signed-off-by: Arnaud Rébillout <rebillout@syscom.ch>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/uemacs/uemacs.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 UEMACS_VERSION = 4.0.15-lt
-UEMACS_SOURCE = em-$(UEMACS_VERSION).tar.bz2
+UEMACS_SOURCE = em-$(UEMACS_VERSION).tar.gz
 UEMACS_SITE = $(BR2_KERNEL_MIRROR)/software/editors/uemacs/
 UEMACS_DEPENDENCIES = ncurses