Update library dependencies to add clangEdit on c-index-test and c-arcmt-test.

To link with -static -lclang, linker tries to seek not libclang.so, clang.dll nor libclang.dll.a, but libclang.a. USEDLIBS should have correct dependencies for -static.
(In contrast, USEDLIBS=libclang.so might be enough w/o -static)

FYI, cygwin build (in buildbot) is using -static, due to avoiding weirdness of extremely slower startup lag of clang.exe.

llvm-svn: 152539