Allow write access to all files if a user has effective root permissions on linux

modules/juce_core/native/juce_posix_SharedCode.h

@@ -332,11 +332,21 @@ uint64 File::getFileIdentifier() const
     return juce_stat (fullPath, info) ? (uint64) info.st_ino : 0;
 }
 
+static bool hasEffectiveRootFilePermissions()
+{
+   #if JUCE_LINUX
+    return (geteuid() == 0);
+   #else
+    return false;
+   #endif
+}
+
 //==============================================================================
 bool File::hasWriteAccess() const
 {
     if (exists())
-        return access (fullPath.toUTF8(), W_OK) == 0;
+        return (hasEffectiveRootFilePermissions()
+             || access (fullPath.toUTF8(), W_OK) == 0);
 
     if ((! isDirectory()) && fullPath.containsChar (separator))
         return getParentDirectory().hasWriteAccess();