brother_mfp: fixes to hopefully satisfy the pipeline.

acinclude.m4

@@ -569,6 +569,13 @@ for be in ${BACKENDS}; do
     fi
     ;;
 
+    brother_mfp)
+    if test "${HAVE_CXX11}" != "1"; then
+      echo "*** $be backend requires C++11 support - $DISABLE_MSG"
+      backend_supported="no"
+    fi
+    ;;
+
     mustek_pp)
     if test "${sane_cv_use_libieee1284}" != "yes" && test "${enable_parport_directio}" != "yes"; then
       echo "*** $be backend requires libieee1284 or parport-directio libraries - $DISABLE_MSG"

backend/brother_mfp-driver.cpp

@@ -61,11 +61,6 @@ const char* BrotherDriver::ScanModeToText (BrotherScanMode scan_mode)
   static const char *scan_mode_text[] =
     { "CGRAY", "GRAY64", "ERRDIF", "TEXT" };
 
-  if (scan_mode > (sizeof(scan_mode_text) / sizeof(scan_mode_text[0])))
-    {
-      return nullptr;
-    }
-
   return scan_mode_text[scan_mode];
 }