clang: do not add -pie for tsan

Revision 220571 removes the requirement to use -pie for tsan binaries. So remove -pie from driver.
Also s/hasZeroBaseShadow/requiresPIE/ because that is what it is used for. Msan does not have zero-based shadow, but requires pie. And in general the relation between zero-based shadow and pie is unclear.

http://reviews.llvm.org/D6318

llvm-svn: 222526