Fix call to strtol
Fix call to strtol

The C standard does not require that errno be set to 0 by strtol in case of
success. It only sets errno in some error conditions.
Simply skip the errno test, since it only informs about underflow of overflow
conditions.

This was introduced by f9502e6842487e3b5f2f7ec27f06d254b1ecebb2 (https://github.com/tbeu/matio/pull/173) for v1.5.22.

tbeu/matio,MaartenBent/matio,tbeu/matio,MaartenBent/matio,tbeu/matio,tbeu/matio,MaartenBent/matio,MaartenBent/matio