Jpegoptim.cの変更なんだけど下記の変更のほうが修正個所が1か所にまとまるしいいかも。

@@ -53,6 +53,39 @@
 #define ICC_IDENT_STRING  "ICC_PROFILE\0"
 #define ICC_IDENT_STRING_SIZE 12

+#ifdef WIN32
+#define uid_t   int
+#define gid_t   int
+#define ROOT_UID	0
+#define ROOT_GID	0
+#define realpath(N,R) _fullpath((R),(N),_MAX_PATH)
+uid_t getuid(void)
+{
+	return ROOT_UID;
+}
+uid_t geteuid(void)
+{
+	return ROOT_UID;
+}
+gid_t getgid(void)
+{
+	return ROOT_GID;
+}
+gid_t getegid(void)
+{
+	return ROOT_GID;
+}
+int setuid(uid_t uid)
+{
+	return (uid == ROOT_UID ? 0 : -1);
+}
+int setgid(gid_t gid)
+{
+	return (gid == ROOT_GID ? 0 : -1);
+}
+
+#endif
+
 void fatal(const char *msg);

 struct my_error_mgr {