liblo: link with libatomic when available

liblo uses atomic builtins that are only available inside libatomic on
some architectures, so link with it when available.

Fixes:

  http://autobuild.buildroot.net/results/c8bed3a3fa7d2b2258f573cbfcb01af07419e0bf/

Signed-off-by: Alex Baldwin <alexbaldwinmusic@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/liblo/liblo.mk

@@ -17,4 +17,10 @@ LIBLO_CONF_OPTS += \
 	--disable-ipv6 \
 	--disable-werror
 
+# Liblo uses atomic builtins, so we need to link with libatomic for
+# the architectures who explicitly need libatomic.
+ifeq ($(BR2_TOOLCHAIN_HAS_LIBATOMIC),y)
+LIBLO_CONF_ENV += LIBS="-latomic"
+endif
+
 $(eval $(autotools-package))