Fix build with -no-feature-regularexpression

The thing we are looking for in qstandardpaths_unix.cpp is
regularexpression, not QT_BOOTSTRAPPED.

Change-Id: I37eb0cdd8a52b0adfd69f592b84659e8807e35ad
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>

src/corelib/global/qconfig-bootstrapped.h

@@ -89,6 +89,7 @@
 #define QT_FEATURE_library -1
 #define QT_NO_QOBJECT
 #define QT_FEATURE_process -1
+#define QT_FEATURE_regularexpression -1
 #define QT_FEATURE_renameat2 -1
 #define QT_FEATURE_sharedmemory -1
 #define QT_FEATURE_slog2 -1

src/corelib/io/qstandardpaths_unix.cpp

@@ -170,7 +170,7 @@ QString QStandardPaths::writableLocation(StandardLocation type)
         break;
     }
 
-#ifndef QT_BOOTSTRAPPED
+#if QT_CONFIG(regularexpression)
     // http://www.freedesktop.org/wiki/Software/xdg-user-dirs
     QString xdgConfigHome = QFile::decodeName(qgetenv("XDG_CONFIG_HOME"));
     if (xdgConfigHome.isEmpty())
@@ -232,7 +232,7 @@ QString QStandardPaths::writableLocation(StandardLocation type)
             }
         }
     }
-#endif
+#endif // QT_CONFIG(regularexpression)
 
     QString path;
     switch (type) {