Fixed two Coverity defects

[dimkr]

1. strlen() on uninitialized string
2. Ignoring the return value of chmod()

[rain-1]

This implements the same change as https://github.com/antirez/linenoise/pull/151

also adds a (void) cast to chmod, I can understand the value of coverity but I don't see this as a valuable addition at the moment.

This patch does not need to be merged.

[dimkr]

I can understand the value of coverity but I don't see this as a valuable addition at the moment.

Compiler warnings aside (unused return value, etc'), the value I see is getting rid of one (useless) Coverity error in every project that uses linenoise upstream as a git submodule.

[Sonophoto]

@rain-1 All of this has been discussed to death, this is done differently than #151, as has been discussed at length as well. @antirez has never chosen to accept these changes but they have been left open if he changes his mind at some future time.

[rain-1]

Merged https://github.com/rain-1/linenoise/commit/6d759a8183d10c7c039d9a8d163ec30a192d24eb