package/pulseview: fix build when linking against libatomic is needed

package/pulseview: fix build when linking against libatomic is needed

With some toolchains, using atomics requires to explicitly add -latomic
to the linker flags.

This change adds a patch to pulseview adding this detection and updating
the LDFLAGS when appropriate.

This patch has be sent upstream:
  http://article.gmane.org/gmane.comp.debugging.sigrok.devel/2097

Fixes:
  http://autobuild.buildroot.org/results/1e3/1e3101261252d5f30fdf842cc99604e4f4c25eef/build-end.log

Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Romain Naour <romain.naour@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>