Run clang-tidy modernize-use-equals-{delete,default} on //courgette

See the bugs and cxx post for justification and details:
https://groups.google.com/a/chromium.org/forum/#!topic/cxx/RkOHzIK6Tq8

This change was done using clang-tidy as described here:
https://chromium.googlesource.com/chromium/src/+/lkcr/docs/clang_tidy.md

In some cases the the tool leaves behind a string of commas where it
replaced a member initializer list
(https://bugs.llvm.org/show_bug.cgi?id=35051). They were cleaned up with:
  git diff --name-only | \
    xargs sed -E -i 's/(^\s*|\)\s*):[ ,]*= default/\1 = default/'

BUG=778959,778957

Change-Id: If5ff4c9b313efb82c9a53d2ea4540c5ef4a9abb0
Reviewed-on: https://chromium-review.googlesource.com/789721
Reviewed-by: Tommi <tommi@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: Chris Watkins <watk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520412}

diff --git a/courgette/adjustment_method_2.cc b/courgette/adjustment_method_2.cc
index 1e60c65f..99c1103 100644
--- a/courgette/adjustment_method_2.cc
+++ b/courgette/adjustment_method_2.cc

@@ -427,7 +427,7 @@
   // VS2005's implementation of std::set<T>::set() requires T to have a copy
   // constructor.
   //   DISALLOW_COPY_AND_ASSIGN(Shingle);
-  void operator=(const Shingle&);  // Disallow assignment only.
+  void operator=(const Shingle&) = delete;  // Disallow assignment only.
 };
 
 std::string ToString(const Shingle* instance) {
@@ -746,7 +746,7 @@
  public:
   typedef std::pair<int, LabelInfo*> ScoreAndLabel;
 
-  VariableQueue() {}
+  VariableQueue() = default;
 
   bool empty() const { return queue_.empty(); }
 
@@ -1225,7 +1225,7 @@
 class Adjuster : public AdjustmentMethod {
  public:
   Adjuster() : prog_(NULL), model_(NULL) {}
-  ~Adjuster() {}
+  ~Adjuster() = default;
 
   bool Adjust(const AssemblyProgram& model, AssemblyProgram* program) {
     VLOG(1) << "Adjuster::Adjust";