cmake: Add variable-length array checks

VLA are more complex thus generating much more code. Alternatives can
be used when VLA are needed.

See: https://outflux.net/slides/2018/lss/danger.pdf - Pages 6, 7 and 8

CMakeLists.txt

@@ -67,8 +67,8 @@ if(${CMAKE_C_COMPILER_ID} MATCHES "Clang" OR ${CMAKE_CXX_COMPILER_ID} MATCHES "C
 endif()
 
 if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_COMPILER_IS_CLANG)
-	set(CMAKE_CXX_FLAGS "-Wall -Wextra -Wno-unused-function -Werror-implicit-function-declaration -Wno-missing-field-initializers ${CMAKE_CXX_FLAGS} -fno-strict-aliasing")
-	set(CMAKE_C_FLAGS "-Wall -Wextra -Wno-unused-function -Werror-implicit-function-declaration -Wno-missing-braces -Wno-missing-field-initializers ${CMAKE_C_FLAGS} -std=gnu99 -fno-strict-aliasing")
+	set(CMAKE_CXX_FLAGS "-Wall -Wextra -Wvla -Wno-unused-function -Werror-implicit-function-declaration -Wno-missing-field-initializers ${CMAKE_CXX_FLAGS} -fno-strict-aliasing")
+	set(CMAKE_C_FLAGS "-Wall -Wextra -Wvla -Wno-unused-function -Werror-implicit-function-declaration -Wno-missing-braces -Wno-missing-field-initializers ${CMAKE_C_FLAGS} -std=gnu99 -fno-strict-aliasing")
 
 	option(USE_LIBC++ "Use libc++ instead of libstdc++" ${APPLE})
 	if(USE_LIBC++)