flex: upgraded package to upstream

Upgraded sys-devel/flex to version 2.6.4-r1 on amd64, arm.

Avoids generating scanners using register keyword, which angers clang++:

  src/compiler/glsl/glsl_lexer.cpp:1629:2: warning: 'register' storage
  class specifier is deprecated and incompatible with C++17
  [-Wdeprecated-register]
        register yy_state_type yy_current_state;

BUG=b:148817989
TEST=emerge mesa and verify that it builds correctly without keyword
    warnings.

Change-Id: I57e9bc0b8994a4c6029b76fd599fa86fae3ed808
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2036458
Tested-by: Kristian H. Kristensen <hoegsberg@chromium.org>
Commit-Queue: Kristian H. Kristensen <hoegsberg@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
8 files changed