This makes the script run to the end and produce tarballs even on test
failures, and then highlights any errors afterwards.
(I first tried just storing the errors in a global variable, but that
didn't work as the "test_llvmCore" function invocation is actually
running as a sub-shell.)
Differential Revision: http://reviews.llvm.org/D11478
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243116 91177308-0d34-0410-b5e6-96231b3b80d8
