Do not link with debug libc on win32 when using cross compile libs. Add delete methods to dstring. Fixes to macOS aarch64 codegen. Use glibc backtrace when available. Add load_* methods to file. The cast (int[8])int_slice[:8] now works.

lib/std/core/string_iterator.c3

@@ -20,4 +20,4 @@ fn Char32! StringIterator.next(&self)
 	Char32 res = conv::utf8_to_char32(&self.utf8[current], &read)!;
 	self.current += read;
 	return res;
-}
+}