setting the sys.executable may also make sense for embedding

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/runtime/PythonOptions.java

@@ -142,7 +142,7 @@ private PythonOptions() {
     @Option(category = OptionCategory.EXPERT, help = "Set by the launcher to the terminal height.") //
     public static final OptionKey<Integer> TerminalHeight = new OptionKey<>(25);
 
-    @Option(category = OptionCategory.EXPERT, help = "The sys.executable path. Set by the launcher, but can may need to be overridden in certain special situations.") //
+    @Option(category = OptionCategory.EXPERT, help = "The sys.executable path. Set by the launcher, but can may need to be overridden in certain special situations.", stability = OptionStability.STABLE) //
     public static final OptionKey<String> Executable = new OptionKey<>("");
 
     @Option(category = OptionCategory.EXPERT, help = "The executed command list as string joined by the executable list separator char. This must always correspond to the real, valid command list used to run GraalPython.") //