package/wireshark: link with -latomic if needed

package/wireshark: link with -latomic if needed

Fix the following build failure raised since bump to version 3.4.7 in
commit bb75c4b541fac144b53b63248e235f22ba1d25ad:

/tmp/instance-5/output-1/host/opt/ext-toolchain/bin/../lib/gcc/sparc-buildroot-linux-uclibc/9.3.0/../../../../sparc-buildroot-linux-uclibc/bin/ld: ui/qt/CMakeFiles/qtui.dir/sequence_diagram.cpp.o: undefined reference to symbol '__atomic_compare_exchange_4@@LIBATOMIC_1.0'
/tmp/instance-5/output-1/host/opt/ext-toolchain/bin/../lib/gcc/sparc-buildroot-linux-uclibc/9.3.0/../../../../sparc-buildroot-linux-uclibc/bin/ld: /tmp/instance-5/output-1/host/sparc-buildroot-linux-uclibc/sysroot/lib/libatomic.so.1: error adding symbols: DSO missing from command line

Fixes:
 - http://autobuild.buildroot.org/results/6617ee0e0046a0452a1515b89e9c704b1c125ec4

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>