builtin: support '-d no_backtrace' directly in panic(), to ease creating .so files with tcc

vlib/builtin/builtin.v

@@ -54,7 +54,10 @@ fn panic_debug(line_no int, file string, mod string, fn_name string, s string) {
 	eprintln('=========================================')
 	$if exit_after_panic_message ? {
 		C.exit(1)
-	}
+	} $else {
+		$if no_backtrace ? {
+			C.exit(1)
+		} $else {
 			$if tinyc {
 				$if panics_break_into_debugger ? {
 					break_if_debugger_attached()
@@ -69,6 +72,8 @@ fn panic_debug(line_no int, file string, mod string, fn_name string, s string) {
 			}
 			C.exit(1)
 		}
+	}
+}
 
 // panic prints a nice error message, then exits the process with exit code of 1.
 // It also shows a backtrace on most platforms.
@@ -76,7 +81,10 @@ pub fn panic(s string) {
 	eprintln('V panic: $s')
 	$if exit_after_panic_message ? {
 		C.exit(1)
-	}
+	} $else {
+		$if no_backtrace ? {
+			C.exit(1)
+		} $else {
 			$if tinyc {
 				$if panics_break_into_debugger ? {
 					break_if_debugger_attached()
@@ -91,6 +99,8 @@ pub fn panic(s string) {
 			}
 			C.exit(1)
 		}
+	}
+}
 
 // eprintln prints a message with a line end, to stderr. Both stderr and stdout are flushed.
 pub fn eprintln(s string) {