flex: update to 2.6.0

Drop backported 0001-bison-test-fixes-Do-not-use-obsolete-bison-construct.patch

Test cases have been completely rearranged upstream, so ptest support
is fully rewritten.

Merge split bb/inc as there's no other user of the .inc [RB]

As automake insists adding BUILD_SOURCES as a dependency to the "all" target,
remove tests/ from the build unless ptests are enabled.  This means native
builds don't need a bison dependency. If ptests are enabled, we build-depend on
flex-native and bison-native for the test suite, and tell it to use the
flex-native binary instead of attempting to run the cross flex it just
built. [RB]

Move in-tree files from files/ to flex/ for consistency. [RB]

(From OE-Core rev: 4fe048b7b32eb3d20a43171b83e8ad2037192d34)

Signed-off-by: Alexander Kanavin <alexander.kanavin@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/flex/flex/disable-tests.patch

@@ -0,0 +1,19 @@
+Due to automake stupidity the Makefile in tests/ has an 'all' target that
+depends on $(BUILD_SOURCES), which means when building flex parts of the test
+suite are built even if they're not needed, resulting in flex needing
+flex-native and bison-native to build.
+
+This patch removes the tests directory from SUBDIRS and will be conditionally
+applied by the recipe.
+
+Upstream-Status: Inappropriate
+Signed-off-by: Ross Burton <ross.burton@intel.com>
+
+diff --git a/Makefile.am b/Makefile.am
+index 076ccad..0574d7b 100644
+--- a/Makefile.am
++++ b/Makefile.am
+@@ -55,3 +55,2 @@ SUBDIRS = \
+ 	po \
+-	tests \
+ 	tools