builtin: remove commented code; improve print_backtrace with tcc

vlib/builtin/builtin.v

@@ -23,15 +23,21 @@ fn on_panic(f fn(int)int) {
 
 // print_backtrace shows a backtrace of the current call stack on stdout
 pub fn print_backtrace() {
-	// at the time of backtrace_symbols_fd call, the C stack would look something like this:
-	// 1 frame for print_backtrace_skipping_top_frames
-	// 1 frame for print_backtrace itself
-	// ... print the rest of the backtrace frames ...
+	// At the time of backtrace_symbols_fd call, the C stack would look something like this:
+	// * print_backtrace_skipping_top_frames
+	// * print_backtrace itself
+	// * the rest of the backtrace frames
 	// => top 2 frames should be skipped, since they will not be informative to the developer
-	$if freestanding {
-		println(bare_backtrace())
-	} $else {
-		print_backtrace_skipping_top_frames(2)
+	$if !no_backtrace ? {
+		$if freestanding {
+			println(bare_backtrace())
+		} $else {
+			$if tinyc {
+				C.tcc_backtrace(c'Backtrace')
+			} $else {
+				print_backtrace_skipping_top_frames(2)
+			}
+		}
 	}
 }