Work around differences in clang libc++ std::vector<bool>::const_reference

clang++ using -stdlib=libc++ defines const_reference as a class,
to map boolean vectors onto a bit set.  Because swig does
not "see" the type as "const &" it generates incorrect code for this case,
generating a declaration like:

  const_reference result;

When const_reference is a typedef to 'bool' as is the case with stdlibc++
this works.  When this is actually a constant reference, this is clearly
invalid since it is not initialized.  For libc++, this is a class
which cannot be default constructed, resulting in an error.  The fix
is to explicitly define the various accessor extensions as having a
bool return type for this specialization.

Lib/csharp/std_vector.i

@@ -217,7 +217,7 @@
         else
           throw std::out_of_range("index");
       }
-      const_reference getitem(int index) throw (std::out_of_range) {
+      CONST_REFERENCE getitem(int index) throw (std::out_of_range) {
         if (index>=0 && index<(int)$self->size())
           return (*$self)[index];
         else

Lib/d/std_vector.i

@@ -128,7 +128,7 @@ public void capacity(size_t value) {
         return $self->capacity() - $self->size();
       }
 
-      const_reference remove() throw (std::out_of_range) {
+      CONST_REFERENCE remove() throw (std::out_of_range) {
         if ($self->empty()) {
           throw std::out_of_range("Tried to remove last element from empty vector.");
         }
@@ -138,7 +138,7 @@ public void capacity(size_t value) {
         return value;
       }
 
-      const_reference remove(size_type index) throw (std::out_of_range) {
+      CONST_REFERENCE remove(size_type index) throw (std::out_of_range) {
         if (index >= $self->size()) {
           throw std::out_of_range("Tried to remove element with invalid index.");
         }
@@ -153,7 +153,7 @@ public void capacity(size_t value) {
     // Wrappers for setting/getting items with the possibly thrown exception
     // specified (important for SWIG wrapper generation).
     %extend {
-      const_reference getElement(size_type index) throw (std::out_of_range) {
+      CONST_REFERENCE getElement(size_type index) throw (std::out_of_range) {
         if ((index < 0) || ($self->size() <= index)) {
           throw std::out_of_range("Tried to get value of element with invalid index.");
         }
@@ -464,7 +464,7 @@ int opApply(int delegate(ref size_t index, ref $typemap(dtype, CTYPE) value) dg)
         return pv;
       }
 
-      const_reference remove() throw (std::out_of_range) {
+      CONST_REFERENCE remove() throw (std::out_of_range) {
         if ($self->empty()) {
           throw std::out_of_range("Tried to remove last element from empty vector.");
         }
@@ -474,7 +474,7 @@ int opApply(int delegate(ref size_t index, ref $typemap(dtype, CTYPE) value) dg)
         return value;
       }
 
-      const_reference remove(size_type index) throw (std::out_of_range) {
+      CONST_REFERENCE remove(size_type index) throw (std::out_of_range) {
         if (index >= $self->size()) {
           throw std::out_of_range("Tried to remove element with invalid index.");
         }
@@ -506,7 +506,7 @@ int opApply(int delegate(ref size_t index, ref $typemap(dtype, CTYPE) value) dg)
     // Wrappers for setting/getting items with the possibly thrown exception
     // specified (important for SWIG wrapper generation).
     %extend {
-      const_reference getElement(size_type index) throw (std::out_of_range) {
+      CONST_REFERENCE getElement(size_type index) throw (std::out_of_range) {
         if ((index < 0) || ($self->size() <= index)) {
           throw std::out_of_range("Tried to get value of element with invalid index.");
         }

Lib/go/std_vector.i

@@ -59,7 +59,7 @@ namespace std {
         %rename(add) push_back;
         void push_back(const value_type& x);
         %extend {
-            const_reference get(int i) throw (std::out_of_range) {
+            bool get(int i) throw (std::out_of_range) {
                 int size = int(self->size());
                 if (i>=0 && i<size)
                     return (*self)[i];

Lib/java/std_vector.i

@@ -61,7 +61,7 @@ namespace std {
         %rename(add) push_back;
         void push_back(const value_type& x);
         %extend {
-            const_reference get(int i) throw (std::out_of_range) {
+            bool get(int i) throw (std::out_of_range) {
                 int size = int(self->size());
                 if (i>=0 && i<size)
                     return (*self)[i];

Lib/php/std_vector.i

@@ -77,7 +77,7 @@ namespace std {
         self->pop_back();
         return x;
       }
-      const_reference get(int i) throw (std::out_of_range) {
+      bool get(int i) throw (std::out_of_range) {
         int size = int(self->size());
         if (i>=0 && i<size)
           return (*self)[i];