Move common header files into a 'support' directory; make 'testit' include -I to that directory; rename 'iterators.h' to 'iterator_test.h'; remove hard-coded paths to include files from more than 350 source files

llvm-svn: 171594
diff --git a/libcxx/test/algorithms/alg.modifying.operations/alg.partitions/partition.pass.cpp b/libcxx/test/algorithms/alg.modifying.operations/alg.partitions/partition.pass.cpp
index 81fb407..8eddfbc 100644
--- a/libcxx/test/algorithms/alg.modifying.operations/alg.partitions/partition.pass.cpp
+++ b/libcxx/test/algorithms/alg.modifying.operations/alg.partitions/partition.pass.cpp
@@ -21,7 +21,7 @@
 #include <memory>
 #endif
 
-#include "../../../iterators.h"
+#include "test_iterators.h"
 
 struct is_odd
 {