Remove dead code. NFC.

This interface was added 2 years ago but users never developed.

llvm-svn: 223368
diff --git a/llvm/unittests/Support/MemoryTest.cpp b/llvm/unittests/Support/MemoryTest.cpp
index 8ad90e0..f439cb2 100644
--- a/llvm/unittests/Support/MemoryTest.cpp
+++ b/llvm/unittests/Support/MemoryTest.cpp
@@ -21,7 +21,7 @@
 public:
   MappedMemoryTest() {
     Flags = GetParam();
-    PageSize = sys::process::get_self()->page_size();
+    PageSize = sys::Process::getPageSize();
   }
 
 protected: