Revert "[libc++] Integrate the PSTL into libc++"

This reverts r366593, which caused unforeseen breakage on the build bots.
I'm reverting until the problems have been figured out and fixed.

llvm-svn: 366603
GitOrigin-RevId: a3c83b7511a56a1bc79784078caab0ad7f8c7abb
diff --git a/test/std/lit.local.cfg b/test/std/lit.local.cfg
deleted file mode 100644
index 6b1e2c6..0000000
--- a/test/std/lit.local.cfg
+++ /dev/null
@@ -1,2 +0,0 @@
-if 'parallel-algorithms' not in config.available_features:
-    config.unsupported = True