Newer compilers (especially clang) warn (and fail) on
`assert (!"message");` constructs typically used to assert on
unreachable code paths (multiple occurrences in jerry-libc). A more
up-to-date approach is to use `assert (false && "message");`. This
patch applies the pattern to all relevant asserts in jerry-libc.
JerryScript-DCO-1.0-Signed-off-by: Akos Kiss [email protected]