add C++ standard library headers for things that are used (nw)

src/lib/netlist/nl_setup.cpp

@@ -17,6 +17,8 @@
 #include "solver/nld_solver.h"
 #include "devices/nlid_truthtable.h"
 
+#include <cmath>
+
 // ----------------------------------------------------------------------------------------
 // setup_t
 // ----------------------------------------------------------------------------------------

src/lib/netlist/plib/palloc.h

@@ -10,8 +10,10 @@
 
 #include "pstring.h"
 
-#include <vector>
+#include <cstddef>
 #include <memory>
+#include <utility>
+#include <vector>
 
 namespace plib {
 

src/lib/netlist/plib/pstring.h

@@ -7,10 +7,11 @@
 #ifndef PSTRING_H_
 #define PSTRING_H_
 
-#include <iterator>
-#include <exception>
-#include <string>
 #include <cstring>
+#include <exception>
+#include <iterator>
+#include <string>
+#include <type_traits>
 
 // ----------------------------------------------------------------------------------------
 // pstring: semi-immutable strings ...