move main to a new source file, update makefile to support multiple sources

neotools/autoextract.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include "neoadpcmextract.h"
+
+
+int main(int argc, char** argv)
+{
+	if (argc != 2)
+		return 1;
+
+	// Open file.
+	FILE* file = fopen(argv[1], "rb");
+	if (!file)
+		return 1;
+
+	int err = vgmExtractSamples(file);
+	fclose(file);
+	return err;
+}