manual: fix missing DL_DIR rename to BR2_DL_DIR

There was one instance of DL_DIR that was left out. Fix that.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
graphs: rename user-facing variables

Rename the GRAPH_OUT and GRAPH_ALT variables according to our
recently-agreed naming scheme for user-facing variables:
  - GRAPH_OUT -> BR2_GRAPH_OUT
  - GRAPH_ALT -> BR2_GRAPH_ALT

The documentation part of the rename is handled by Thomas as
part of his manual fixing spree. ;-)

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
common-usage.txt: adjust documentation for renamed BR2_GRAPH_ variables

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
thrift: needs host-bison and host-flex

Fixes:

  http://autobuild.buildroot.org/results/d46/d46f9097780bdde68ec15f693281ee0b04667f98/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
libsigsegv: add Blackfin support

Fixes:

 http://autobuild.buildroot.org/results/5e2/5e2c627cfcb2699b16a82eb9554f2c9dfabd5483/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Merge remote-tracking branch 'mirror/master'