tweak

git-svn-id: https://svn.r-project.org/R/trunk@62861 00db46b3-68df-0310-9c12-caf00c1e9a41
update PCRE to 8.33

git-svn-id: https://svn.r-project.org/R/trunk@62863 00db46b3-68df-0310-9c12-caf00c1e9a41
update

git-svn-id: https://svn.r-project.org/R/trunk@62864 00db46b3-68df-0310-9c12-caf00c1e9a41
Make R_Srcref a GC root; probably not necessary but better to be safe.


git-svn-id: https://svn.r-project.org/R/trunk@62865 00db46b3-68df-0310-9c12-caf00c1e9a41