gstreamer: add legal info

Even though COPYING is LGPLv2+ many code files state v2.1+

Signed-off-by: Gustavo Zacarias <gustavo.zacarias@free-electrons.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gstreamer/gstreamer/gstreamer.mk

@@ -8,6 +8,9 @@ GSTREAMER_VERSION = 0.10.36
 GSTREAMER_SOURCE = gstreamer-$(GSTREAMER_VERSION).tar.xz
 GSTREAMER_SITE = http://gstreamer.freedesktop.org/src/gstreamer
 GSTREAMER_INSTALL_STAGING = YES
+# COPYING is in fact v2, but most of the code is v2.1+
+GSTREAMER_LICENSE = LGPLv2.1+
+GSTREAMER_LICENSE_FILES = COPYING
 
 # Checking if unaligned memory access works correctly cannot be done when cross
 # compiling. For the following architectures there is no information available