[COFF] support /ERRORLIMIT option

Summary: This adds support for reporting multiple errors in a single invocation of lld-link. The limit defaults to 20 and can be changed with the /ERRORLIMIT command line parameter, or set to unlimited by passing a value of 0.

Reviewers: pcc, ruiu

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D29691

llvm-svn: 295507