gioerror: Map ETXTBSY to G_FILE_ERROR_BUSY

It's a busy text file, but we don't care much about specifics so we
can just return the generic busy error.

gio/gioerror.c

@@ -224,6 +224,12 @@ g_io_error_from_errno (gint err_no)
       break;
 #endif
 
+#ifdef ETXTBSY
+    case ETXTBSY:
+      return G_IO_ERROR_BUSY;
+      break;
+#endif
+
 #ifdef EWOULDBLOCK
     case EWOULDBLOCK:
       return G_IO_ERROR_WOULD_BLOCK;

gio/tests/error.c

@@ -287,7 +287,7 @@ test_error_from_errno (void)
 
 #ifdef ETXTBSY
   g_assert_cmpint (g_io_error_from_errno (ETXTBSY), ==,
-                   G_IO_ERROR_FAILED);
+                   G_IO_ERROR_BUSY);
 #endif
 
 #ifdef EFBIG