support/graph-depends: drop legacy target-exceptions

support/graph-depends: drop legacy target-exceptions

Currently, we avoid drawing the dependencies that we call 'target
exceptions', becasue they initially were returned by 'show-targets',
when they in fact were not really packages and thus should not be on
the graph.

However, those two exceptions have no longer been reported in the output
of show-targets since we merged very old initial top-level parallel
build way back in 2014, with commit a24877586a56 (Makefile: add support
for top-level parallel make), where they had been converted into purely
internal rules.

4 years have passed, we can now drop those exceptions from the
graph-depends script.

This concludes the cleanup initiated three years ago with commit
0b32791f0076 (graph-depends: remove absent targets from
TARGET_EXCEPTIONS).

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>