Bump buidlroot version to 2018.02.6

bsp/buildroot/package/brltty/0004-buildsys-fix-cross-compilation.patch

@@ -0,0 +1,41 @@
+From 088666535a045dae71bd2fcc6b3a1553023106ce Mon Sep 17 00:00:00 2001
+From: "Yann E. MORIN" <yann.morin.1998@free.fr>
+Date: Wed, 22 Aug 2018 10:10:19 +0200
+Subject: [PATCH] buildsys: fix cross-compilation
+
+Some identifiers for includes and libs paths may contain digit, e.g.
+X11_PACKAGE or ATSPI2_PACKAGE or GLIB2_PACKAGE...
+
+Also detect those identifiers when doing cros-compilation, so that the
+_FOR_BUILD variants are really created and do not clash with the target
+variants.
+
+Fixes:
+    http://autobuild.buildroot.org/results/a37/a37782b3cfc1a96cc129db8fade20a36a7b2d470/build-end.log
+    http://autobuild.buildroot.org/results/97e/97edc6a47d2140968e84b409cdc960604e5896f2/build-end.log
+    [...]
+
+Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
+---
+Upstram status: submitted
+https://github.com/brltty/brltty/pull/142
+---
+ mk4build | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/mk4build b/mk4build
+index db90c86a9..551283825 100755
+--- a/mk4build
++++ b/mk4build
+@@ -112,7 +112,7 @@ fi
+ 
+ sedScript="${outputName}.${sedExtension}"
+ sed -n -e '
+-s/^ *\([A-Za-z][A-Za-z_]*\) *=.*$/\1/
++s/^ *\([A-Za-z][A-Za-z0-9_]*\) *=.*$/\1/
+ t found
+ d
+ :found
+-- 
+2.14.1
+