tcp: Explicitly convert a pointer to a boolean integer

This fixes warnings about making integers from pointers without
a cast, and avoids the theoretical case where the lower 32 bits of
the pointer would all be zero where the implicit cast wouldn't give
the right result.

Signed-off-by: Martin Storsjö <martin@martin.st>
movenc: Add a warning message if conflicting options have been specified

Signed-off-by: Martin Storsjö <martin@martin.st>
movenc: Simplify setting the fragmentation flag

This makes sure the faststart vs fragmentation check works as
intended when fragmentation is enabled due to using the ismv mode.

Signed-off-by: Martin Storsjö <martin@martin.st>