Add makefile, and move latlon to a 'tools' directory

helpers/tools/Makefile

@@ -0,0 +1,24 @@
+bin := latlon
+
+CC = gcc
+
+CFLAGS += -Wall
+CFLAGS += -Wextra
+CFLAGS += -Wpedantic
+CFLAGS += -std=c23
+CFLAGS += -O3
+
+LDFLAGS += -lm
+
+PREFIX ?= $(HOME)/.local/share/dzgui
+
+all: $(bin)
+
+install: $(bin)
+	install -Dm 755 $(bin) $(PREFIX)
+
+$(bin): latlon.c
+	$(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS)
+
+clean:
+	rm -f $(bin)