Had to change soname to install_name on macos, but I don't really know

why.

https://stackoverflow.com/questions/4580789/ld-unknown-option-soname-on-os-x

-	$(CC) $(CFLAGS) $(LDFLAGS) -shared -Wl,-soname,$(SONAME) -o $@ $(MAIN_O)
+	$(CC) $(CFLAGS) $(LDFLAGS) -shared -Wl,-install_name,$(SONAME) -o $@ $(MAIN_O)

makefile

@@ -132,7 +132,7 @@ lib/libmonocypher.so: lib/$(SONAME)
  ln -sf `basename lib/$(SONAME)` $@
 
 lib/$(SONAME): $(MAIN_O)
- $(CC) $(CFLAGS) $(LDFLAGS) -shared -Wl,-soname,$(SONAME) -o $@ $(MAIN_O)
+ $(CC) $(CFLAGS) $(LDFLAGS) -shared -Wl,-install_name,$(SONAME) -o $@ $(MAIN_O)
 
 lib/monocypher.o: src/monocypher.c src/monocypher.h
  @mkdir -p $(@D)