gst-plugins-bad: attempt to fix problem with 'glib-mkenums'

Error was (build time):
/data/data/com.termux/files/usr/bin/glib-mkenums: line 10: from: command not found
/data/data/com.termux/files/usr/bin/glib-mkenums: line 12: import: command not found
/data/data/com.termux/files/usr/bin/glib-mkenums: line 13: import: command not found

packages/gst-plugins-bad/build.sh

@@ -21,4 +21,5 @@ TERMUX_PKG_RM_AFTER_INSTALL="share/gtk-doc/"
 termux_step_pre_configure() {
 	export GNUSTL_LIBS="-lc"
 	export GNUSTL_CFLAGS="-Oz"
+	export GLIB_MKENUMS="/usr/bin/glib-mkenums"
 }