Revert "Merge pull request #1725 from atrick/specialize"

Temporarily reverting @_specialize because stdlib unit tests are
failing on an internal branch during deserialization.

This reverts commit e2c43cfe14, reversing
changes made to 9078011f93.

lib/SIL/SILFunction.cpp

@@ -25,19 +25,6 @@
 using namespace swift;
 using namespace Lowering;
 
-SILSpecializeAttr::SILSpecializeAttr(ArrayRef<Substitution> subs)
-  : numSubs(subs.size()) {
-  std::copy(subs.begin(), subs.end(), getTrailingObjects<Substitution>());
-}
-
-SILSpecializeAttr *SILSpecializeAttr::create(SILModule &M,
-                                             ArrayRef<Substitution> subs) {
-  unsigned size =
-    sizeof(SILSpecializeAttr) + (subs.size() * sizeof(Substitution));
-  void *buf = M.allocate(size, alignof(SILSpecializeAttr));
-  return ::new (buf) SILSpecializeAttr(subs);
-}
-
 SILFunction *SILFunction::create(SILModule &M, SILLinkage linkage,
                                  StringRef name,
                                  CanSILFunctionType loweredType,