Set C11 in all compilers.

I'm not sure why I conditioned C11 on non-Clang MSVC. I think I meant to
invert that condition to NOT MSVC OR CLANG. But given that it worked,
just do it across the board.

(Though we support VS2017, which doesn't support a C11 mode, so this is
slightly curious. It may just be that pre-VS2019, this option is a
no-op.)

Change-Id: I271ffd2a913c1aa676fea7ec41f30c1896bb5955
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/56325
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4c39d12..6085713 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -125,10 +125,8 @@
 
 set(CMAKE_CXX_STANDARD 14)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
-if(MSVC AND NOT CLANG)
-  set(CMAKE_C_STANDARD 11)
-  set(CMAKE_C_STANDARD_REQUIRED ON)
-endif()
+set(CMAKE_C_STANDARD 11)
+set(CMAKE_C_STANDARD_REQUIRED ON)
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CLANG)
   # Note clang-cl is odd and sets both CLANG and MSVC. We base our configuration