Added declaration and implementations of `void abort (void)` to
jerry-libc. As the linux implementation relies on the `getpid`
syscall - which has no arguments - `syscall_0` implementations
have been added as well.
`libc_fatal` has been adapted to use the new `abort` function
instead of `exit`. This also made the definition of
`LIBC_FATAL_ERROR_EXIT_CODE` unnecessary.
Finally, the syscall fatal error message was fixed.
JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu
