Make BASH_LAUNCHER_EXEC_NAME protected

Author: fangerer

graalpython/com.oracle.graal.python.shell/src/com/oracle/graal/python/shell/GraalPythonMain.java

@@ -70,7 +70,7 @@ public static void main(String[] args) {
     private static final String MIME_TYPE = "text/x-python";
 
     // provided by GraalVM bash launchers, ignored in native image mode
-    private static final String BASH_LAUNCHER_EXEC_NAME = System.getProperty("org.graalvm.launcher.executablename");
+    protected static final String BASH_LAUNCHER_EXEC_NAME = System.getProperty("org.graalvm.launcher.executablename");
 
     private static long startupWallClockTime = -1;
     private static long startupNanoTime = -1;