Fix Pi build needing -latomic. Issue #6275.

src/Makefile

@@ -77,6 +77,15 @@ FINAL_LDFLAGS=$(LDFLAGS) $(REDIS_LDFLAGS) $(DEBUG)
 FINAL_LIBS=-lm
 DEBUG=-g -ggdb
 
+# Linux ARM needs -latomic at linking time
+ifneq (,$(filter aarch64 armv,$(uname_M)))
+        FINAL_LIBS+=-latomic
+else
+ifneq (,$(findstring armv,$(uname_M)))
+        FINAL_LIBS+=-latomic
+endif
+endif
+
 ifeq ($(uname_S),SunOS)
 	# SunOS
         ifneq ($(@@),32bit)