misc: clang-11 and gcc-10 support

clang-11 complains:

 error: field 'buffer_template' with variable sized type 'vlib_buffer_t' not at the end of a struct or class is a GNU extension [-Werror,-Wgnu-variable-sized-type-not-at-end]

Type: improvement
Change-Id: I2cb6b4fde723a05b42cf33dd8130df074f0362ab
Signed-off-by: Damjan Marion <damarion@cisco.com>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 499a39f..0d971fd 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -13,7 +13,7 @@
 
 cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
 
-set(CMAKE_C_COMPILER_NAMES clang-10 clang-9 gcc-9 cc)
+set(CMAKE_C_COMPILER_NAMES clang-11 clang-10 clang-9 gcc-10 gcc-9 cc)
 
 project(vpp C)