Reduce level of -Wformat-truncation

Reduce level of format truncation warnings due to issues with false
positives (an unknown size buffer is always treated as size 1)

Signed-off-by: Paul Elliott <paul.elliott@arm.com>

Author: paul-elliott-arm

mbedtls-sys/vendor/CMakeLists.txt

@@ -198,7 +198,7 @@ if(CMAKE_COMPILER_IS_GNU)
         endif()
     endif()
     if (GCC_VERSION VERSION_GREATER 7.0 OR GCC_VERSION VERSION_EQUAL 7.0)
-      set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wformat-overflow=2 -Wformat-truncation=2")
+      set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wformat-overflow=2 -Wformat-truncation")
     endif()
     set(CMAKE_C_FLAGS_RELEASE     "-O2")
     set(CMAKE_C_FLAGS_DEBUG       "-O0 -g3")