Add FunctionDecl::getParameterSourceRange()

This source range covers the list of parameters of the function declaration,
including the ellipsis for a variadic function.
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index abfa33d..eb02a61 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -3875,10 +3875,11 @@
   auto ESH = FunctionProtoType::getExceptionSpecSize(
       EPI.ExceptionSpec.Type, EPI.ExceptionSpec.Exceptions.size());
   size_t Size = FunctionProtoType::totalSizeToAlloc<
-      QualType, FunctionType::FunctionTypeExtraBitfields,
+      QualType, SourceLocation, FunctionType::FunctionTypeExtraBitfields,
       FunctionType::ExceptionType, Expr *, FunctionDecl *,
       FunctionProtoType::ExtParameterInfo, Qualifiers>(
-      NumArgs, FunctionProtoType::hasExtraBitfields(EPI.ExceptionSpec.Type),
+      NumArgs, EPI.Variadic,
+      FunctionProtoType::hasExtraBitfields(EPI.ExceptionSpec.Type),
       ESH.NumExceptionType, ESH.NumExprPtr, ESH.NumFunctionDeclPtr,
       EPI.ExtParameterInfos ? NumArgs : 0,
       EPI.TypeQuals.hasNonFastQualifiers() ? 1 : 0);