tools/flex: update to 2.6.1

Update flex to 2.6.1
* Flex has moved to Github, adjust download link
* Remove patch that has been applied upstream
* Disable building tests to avoid circular dependency to bison
  - disable also docs and examples at the same time

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>

SVN-Revision: 49025

tools/flex/patches/100-disable-tests-docs.patch

@@ -0,0 +1,13 @@
+--- a/Makefile.am
++++ b/Makefile.am
+@@ -45,10 +45,7 @@
+ SUBDIRS = \
+ 	lib \
+ 	src \
+-	doc \
+-	examples \
+ 	po \
+-	tests \
+ 	tools
+ 
+ # Create the ChangeLog, but only if we're inside a git working directory