fwts: pcre breaks on arm 32 because of incorrect size of vector in klog lib helper

fwts klog regular expressions break pcre on arm 32 with a stack smashing overflow. This is because the vector passed to pcre_exec must be a multiple of 3 in size and fwts is only using 1. Also it would be useful if pcre_exec errors are reported in case the regular expressions are corrupt or mis-compiled at run time to catch other pcre issues in the future.