put entry point in calcite library

src/user-apps/hello/hello.c

@@ -17,8 +17,7 @@
 
 #include <calcite/calcite.h>
 
-[[noreturn]]
-void _start() {
+void main() {
 
   struct framebuffer_info fb_info;
   map_framebuffer(&fb_info);
@@ -30,6 +29,4 @@ void _start() {
       pixel[1] = y * 256 / fb_info.fb_height;
     }
 
-  end_thread();
-
 }

src/user-libs/calcite/entry.c

@@ -0,0 +1,25 @@
+/* Calcite, src/user-libs/calcite/entry.c
+ * Copyright 2025 Benji Dial
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <calcite/calcite.h>
+
+void main();
+
+[[noreturn]] void _start() {
+  main();
+  end_thread();
+}