Change the parameters of start

On the switch, `start` takes two parameters : an exception pointer,
and a handle to the main thread. For libtransistor, we'll also add
a third one: a context handle. This should allow ace_loader to start
apps expecting the usual switch treatment, while still providing the
context to libtransistor binaries.

Author: roblabla

lib/crt0.nro.S

@@ -41,7 +41,7 @@ _mod_header:
 start:
         sub sp, sp, 0x10
         stp x29, x30, [sp]
-        adrp x1, _start // aslr base
+        adrp x3, _start // aslr base
         bl _libtransistor_start
         ldp x29, x30, [sp], 0x10
         ret

lib/crt0.nso.S

@@ -37,7 +37,7 @@ _mod_header:
 
 .section .text, "e"
 start:
-        adrp x1, _start // aslr base
+        adrp x3, _start // aslr base
 	bl _libtransistor_start
 loop:
 .global _exit

lib/crt0_common.c

@@ -119,14 +119,19 @@ static int socklog_read(struct _reent *reent, void *v, char *ptr, int len) {
 #define DEFAULT_NOCONTEXT_HEAP_SIZE 0x400000
 
 static bool dont_finalize_bsd = false;
+static thread_h MAIN_HANDLE;
 
-int _libtransistor_start(libtransistor_context_t *ctx, void *aslr_base) {
+int _libtransistor_start(void *exception_info_ptr, thread_h main_handle, libtransistor_context_t *ctx, void *aslr_base) {
 	if(relocate(aslr_base)) {
 		return -4;
 	}
 
 	__guard_setup();
-	
+
+	MAIN_HANDLE = main_handle;
+
+	dbg_printf("exception_ptr: %x", exception_info_ptr);
+	dbg_printf("main handle: %x", main_handle);
 	dbg_printf("aslr base: %p", aslr_base);
 	dbg_printf("ctx: %p", ctx);