newt: avoid poisoned paths

Fixes http://autobuild.buildroot.net/results/cb908f73b14e1510bea890167b3927afbf708d6f/

Signed-off-by: Alex Suykov <alex.suykov@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/newt/0002-slang-include-dir.patch

@@ -0,0 +1,15 @@
+slang.h is in sysroot/usr/include, no need to use -I
+
+Signed-off-by: Alex Suykov <alex.suykov@gmail.com>
+
+--- a/Makefile.in
++++ b/Makefile.in
+@@ -5,7 +5,7 @@
+ CPP = @CPP@
+ CFLAGS = @CFLAGS@
+ LDFLAGS = @LDFLAGS@
+-CPPFLAGS = -D_GNU_SOURCE -I/usr/include/slang @CPPFLAGS@ 
++CPPFLAGS = -D_GNU_SOURCE @CPPFLAGS@ 
+ GNU_LD = @GNU_LD@
+ 
+ VERSION = @VERSION@