Fix for PR 16046, null chars in strings

git-svn-id: https://svn.r-project.org/R/trunk@66924 00db46b3-68df-0310-9c12-caf00c1e9a41
Fix for PR#16047, abs(x=1i) error.

git-svn-id: https://svn.r-project.org/R/trunk@66926 00db46b3-68df-0310-9c12-caf00c1e9a41
Allow different test directory

git-svn-id: https://svn.r-project.org/R/trunk@66928 00db46b3-68df-0310-9c12-caf00c1e9a41