Rename Action::begin() to Action::input_begin().

Also introduce inputs() that reutnrs an llvm::iterator_range.
Iterating over A->inputs() is much less mysterious than
iterating over *A.  No intended behavior change.

llvm-svn: 261674
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 235d760..2991189 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2471,8 +2471,8 @@
   if (isa<CompileJobAction>(A) || isa<BackendJobAction>(A))
     return true;
 
-  for (const auto &Act : *A)
-    if (ContainsCompileAction(Act))
+  for (const auto &AI : A->inputs())
+    if (ContainsCompileAction(AI))
       return true;
 
   return false;