Colouring trailing whitespace in Makefiles, patch by Mike Frysinger.

git-svn-id: svn://svn.savannah.gnu.org/nano/trunk/nano@4617 35c25a1d-7b9e-4130-9fde-d3aeb78583b8

ChangeLog

@@ -5,6 +5,7 @@
 	* doc/syntax/gentoo.nanorc - Update to newer EAPIs, and fold
 	in updated shell changes too.  Much of this is based on work
 	by Davide Pesavento <pesa@gentoo.org>.
+	* doc/syntax/makefile.nanorc: Highlight trailing whitespace.
 
 2014-02-26  Benno Schulenberg  <bensberg@justemail.net>
 	* src/global.c (shortcut_init) -  Put PageUp and PageDown

doc/syntax/makefile.nanorc

@@ -7,3 +7,5 @@ color magenta "\<(if|ifeq|else|endif)\>"
 color blue "\$+[{(][a-zA-Z0-9_-]+[})]"
 color brightblue "^[^ 	]+:"
 color green "#.*$"
+## Trailing whitespace.
+color ,green "[[:space:]]+$"