devtools: relax rule for identifying symbol section

devtools: relax rule for identifying symbol section

It was reported recently that some patches that add symbols to an
existing EXPERIMENTAL section of a version map file generate errors
because the check-symbol-change script was identifying the section as
"@@" rather than EXPERIMENTAL.  This was fairly clearly due to the fact
that the rule identifying the version section expected the whole section
to be added, rather than having it already exist, with only new symbols
being added to the existing section. This led the match rule to misread
the format of that line and pull the wrong word out of it.

The fix is to relax the rule slightly.  Rather than assume that the
section must exist on a line that was added, allow the section name to
be set by any line that ends in a '{', which should be correct, given
our coding practices.  The section name is then extracted as the next to
the last word on the line ( $(NF-1) ).

Fixes: 4bec48184e33 ("devtools: add checks for ABI symbol addition")
Cc: stable@dpdk.org
Reported-by: Nikhil Rao <nikhil.rao@intel.com>
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Tested-by: Nikhil Rao <nikhil.rao@intel.com>