Rewrote crt0, init, and chainloading code

start.s, init.c, linker.ld and linker.specs are meant
to be re-used by user applications, should they remove the defines
from init.c and the .chainloader* sections from the linker script

fusee/fusee-primary/src/chainloader.c

@@ -0,0 +1,34 @@
+#include "chainloader.h"
+
+char g_chainloader_arg_data[CHAINLOADER_ARG_DATA_MAX_SIZE] = {0};
+chainloader_entry_t g_chainloader_entries[CHAINLOADER_MAX_ENTRIES] = {0}; /* keep them sorted */
+size_t g_chainloader_num_entries = 0;
+uintptr_t g_chainloader_entrypoint = 0;
+
+#pragma GCC optimize (3)
+
+static void *xmemmove(void *dst, const void *src, size_t len)
+{
+    const uint8_t *src8 = (const uint8_t *)src;
+    uint8_t *dst8 = (uint8_t *)dst;
+
+    if (dst8 < src8) {
+        for (size_t i = 0; i < len; i++) {
+            dst8[i] = src8[i];
+        }
+    } else if (src8 > dst8) {
+        for (size_t i = len; len > 0; len--)
+            dst8[i - 1] = src8[i - 1];
+    }
+
+    return dst;
+}
+
+void relocate_and_chainload_main(int argc) {
+    for(size_t i = 0; i < g_chainloader_num_entries; i++) {
+        chainloader_entry_t *entry = &g_chainloader_entries[i];
+        xmemmove((void *)entry->load_address, (const void *)entry->src_address, entry->size);
+    }
+
+    ((void (*)(int, void *))g_chainloader_entrypoint)(argc, g_chainloader_arg_data);
+}