cgen: fix VUNREACHABLE on freebsd/tcc

cmd/tools/fast/fast.v

@@ -116,6 +116,7 @@ fn exec(s string) string {
 fn measure(cmd string, description string) int {
 	println('  Measuring $description')
 	println('  Warming up...')
+	println(cmd)
 	for _ in 0 .. 3 {
 		exec(cmd)
 	}

vlib/v/gen/c/cheaders.v

@@ -200,6 +200,9 @@ const c_common_macros = '
 	#ifndef VUNREACHABLE
 		#define VUNREACHABLE() do { } while (0)
 	#endif
+	#if defined(__FreeBSD__) && defined(__TINYC__)
+		#define VUNREACHABLE() do { } while (0)
+	#endif
 #endif
 
 //likely and unlikely macros