Stop enforcing C99 in CMakeLists.txt

This allows us to sometimes use C11 features.

Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 36baa3b..210cc38 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -177,9 +177,6 @@
 
 include(CheckCCompilerFlag)
 
-set(CMAKE_C_EXTENSIONS OFF)
-set(CMAKE_C_STANDARD 99)
-
 if(CMAKE_COMPILER_IS_GNU)
     # some warnings we want are not available with old GCC versions
     # note: starting with CMake 2.8 we could use CMAKE_C_COMPILER_VERSION