destiny: fixed condition for error handling
send_tcp returns either the length of the sent data,
or -1, if an error was detected.

The current implementation checks for != 1.
This results in executing the error case, although
there was semantically no error returned from send_tcp.
Merge pull request #1280 from cgundogan/fix_send_tcp_error_check

destiny: fixed condition for error handling of send_tcp in destiny_socket_send
make: remove local definitions of (ELF|HEX)FILE

We have sane defaults for `ELFFILE` and `HEXFILE` in the root
`Makefile.include`. The local definition for `ELFFILE` of mbed_lpc1768's
`Makefile.include` was wrong, which caused e.g. `make buildsize` to
fail.
Merge pull request #1303 from Kijewski/mbed_lpc1768-fix-result-paths

make: remove local definitions for ELFFILE and HEXFILE (was: "mbed_lpc1768: fix ELF and HEX paths")