WIP: Switch to compiler-rt sync on armv7

lib/libcompiler_rt/Makefile.inc

@@ -270,6 +270,13 @@ SRCF+=		truncsfbf2
 
 SRCF+=		stdatomic
 CFLAGS+=	-DEMIT_SYNC_ATOMICS
+
+#.for op in add and max min nand or sub umax umin xor
+#. for size in 4 8
+#SRCF+=		sync_fetch_and_${op}_${size}
+#. endfor
+#.endfor
+
 .endif
 
 .for file in ${SRCF}