Bug #80124 for Params-Validate: validate clobbers $@

Hi Dave, I have found that the validate function clears the value of $@. This can cause really nasty bugs, for instance, I found it when using Log::Log4perl (that uses Params::Validate under the hood) in the following manner:   eval { ... };   DEBUG "error: $@";   if ($@) {     # handle error   } DEBUG calls validate that resets $@ and so the error handling code is never executed. After looking at Params::Validate code I found that the root of the problem is that it uses eval_pv to find the caller module from get_options. The attached patch changes it to obtain it directly from the opcode calling validate. I have also added a new test file that checks that $@ is not clobbered. There is another usage of eval_pv on the code but it is not called from the non-failure code path, so I have left it unchanged. If you want I could also replace it by pure XS code. Cheers,  - Salva