Split GenFunc.cpp in three: GenFunc for function types and blocks,

GenCall for function signatures, calls, and prologue/epilogue, and
GenBuiltin for builtin operations.

NFC.

Author: rjmccall

lib/IRGen/CMakeLists.txt

@@ -4,6 +4,8 @@ add_swift_library(swiftIRGen
   ExtraInhabitants.cpp
   Fulfillment.cpp
   GenArchetype.cpp
+  GenBuiltin.cpp
+  GenCall.cpp
   GenCast.cpp
   GenClangDecl.cpp
   GenClangType.cpp

lib/IRGen/Callee.h

@@ -21,32 +21,21 @@
 #include <type_traits>
 #include "llvm/IR/DerivedTypes.h"
 #include "swift/SIL/SILType.h"
-#include "CallingConvention.h"
 #include "Explosion.h"
 #include "IRGen.h"
+#include "Signature.h"
 
 namespace llvm {
   class PointerType;
 }
 
-namespace clang {
-  namespace CodeGen {
-    class CGFunctionInfo;    
-  }
-}
-
 namespace swift {
   class Substitution;
 
 namespace irgen {
   class Callee;
   class IRGenFunction;
 
-  class ForeignFunctionInfo {
-  public:
-    const clang::CodeGen::CGFunctionInfo *ClangInfo = nullptr;
-  };
-
   class Callee {
     /// The unsubstituted function type being called.
     CanSILFunctionType OrigFnType;