vlib: convert foreach_vlib_main macro to be more gdb and clang-format friendly

Type: improvement
Change-Id: I1152e58d7bfcb3c4347147f87a834d45ad51cdfe
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/.clang-format b/.clang-format
index 8b5c955..bce671f 100644
--- a/.clang-format
+++ b/.clang-format
@@ -18,4 +18,5 @@
   - 'vec_foreach_index'
   - 'vec_foreach_index_backwards'
   - 'vlib_foreach_rx_tx'
+  - 'foreach_vlib_main'