package/php: link with -latomic if needed

Fixes:
http://autobuild.buildroot.net/results/112/112ec5cb0de6f55a29caf7ec563367afd28eb8a0/

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

package/php/php.mk

@@ -35,6 +35,10 @@ ifeq ($(BR2_STATIC_LIBS)$(BR2_TOOLCHAIN_HAS_THREADS),yy)
 PHP_STATIC_LIBS += -lpthread
 endif
 
+ifeq ($(BR2_TOOLCHAIN_HAS_LIBATOMIC),y)
+PHP_EXTRA_LIBS += -latomic
+endif
+
 ifeq ($(call qstrip,$(BR2_TARGET_LOCALTIME)),)
 PHP_LOCALTIME = UTC
 else