deimos.curses: Fix NCURSES_OPAQUE builds

Fix bindings when NCURSES_OPAQUE is defined, and define it implicitly
when NCURSES_REENTRANT is set (which is what the ncurses configure
script does).

Author: CyberShadow

source/deimos/curses.di

@@ -38,6 +38,14 @@ module deimos.curses;
 
 extern (C):
 
+/*
+ * NCURSES_REENTRANT implies NCURSES_OPAQUE (as in the C configure script).
+ * See ncurses configure.in lines 1377-1388.
+ */
+version (NCURSES_REENTRANT) {
+    version = NCURSES_OPAQUE;
+}
+
 /*
  The symbols beginning NCURSES_ or USE_ are configuration choices.
  A few of the former can be overridden by applications at compile-time.
@@ -124,10 +132,26 @@ alias NCURSES_PAIRS_T = short;
  * Definitions used to make WINDOW and similar structs opaque.
  */
 version (NCURSES_INTERNALS) {} else {
-enum NCURSES_OPAQUE       = 0;
-enum NCURSES_OPAQUE_FORM  = 0;
-enum NCURSES_OPAQUE_MENU  = 0;
-enum NCURSES_OPAQUE_PANEL = 0;
+version (NCURSES_OPAQUE) {
+    enum NCURSES_OPAQUE       = 1;
+} else {
+    enum NCURSES_OPAQUE       = 0;
+}
+version (NCURSES_OPAQUE_FORM) {
+    enum NCURSES_OPAQUE_FORM  = 1;
+} else {
+    enum NCURSES_OPAQUE_FORM  = 0;
+}
+version (NCURSES_OPAQUE_MENU) {
+    enum NCURSES_OPAQUE_MENU  = 1;
+} else {
+    enum NCURSES_OPAQUE_MENU  = 0;
+}
+version (NCURSES_OPAQUE_PANEL) {
+    enum NCURSES_OPAQUE_PANEL = 1;
+} else {
+    enum NCURSES_OPAQUE_PANEL = 0;
+}
 }
 
 /*
@@ -460,6 +484,9 @@ version (all) {
 }
 }
 }
+} else { /* NCURSES_OPAQUE */
+/* Opaque struct - only WINDOW* pointers can be used */
+struct _win_st;
 } /* NCURSES_OPAQUE */
 
 /*
@@ -772,15 +799,21 @@ extern nothrow @nogc char * tiparm (const(char) *, ...);               /* specia
 /*
  * These functions are not in X/Open, but we use them in macro definitions:
  */
-// extern nothrow @nogc int getattrs (const(WINDOW) *);                   /* generated */
-// extern nothrow @nogc int getcurx (const(WINDOW) *);                    /* generated */
-// extern nothrow @nogc int getcury (const(WINDOW) *);                    /* generated */
-// extern nothrow @nogc int getbegx (const(WINDOW) *);                    /* generated */
-// extern nothrow @nogc int getbegy (const(WINDOW) *);                    /* generated */
-// extern nothrow @nogc int getmaxx (const(WINDOW) *);                    /* generated */
-// extern nothrow @nogc int getmaxy (const(WINDOW) *);                    /* generated */
-// extern nothrow @nogc int getparx (const(WINDOW) *);                    /* generated */
-// extern nothrow @nogc int getpary (const(WINDOW) *);                    /* generated */
+// The functions in the block below are overridden in C
+// by macros (see `if (!NCURSES_OPAQUE)` lower in this file).
+// D does not have an equivalent to macros which override previously
+// defined functions, so we make these conditional instead.
+static if (NCURSES_OPAQUE) {
+extern nothrow @nogc int getattrs (const(WINDOW) *);                   /* generated */
+extern nothrow @nogc int getcurx (const(WINDOW) *);                    /* generated */
+extern nothrow @nogc int getcury (const(WINDOW) *);                    /* generated */
+extern nothrow @nogc int getbegx (const(WINDOW) *);                    /* generated */
+extern nothrow @nogc int getbegy (const(WINDOW) *);                    /* generated */
+extern nothrow @nogc int getmaxx (const(WINDOW) *);                    /* generated */
+extern nothrow @nogc int getmaxy (const(WINDOW) *);                    /* generated */
+extern nothrow @nogc int getparx (const(WINDOW) *);                    /* generated */
+extern nothrow @nogc int getpary (const(WINDOW) *);                    /* generated */
+}
 
 /*
  * vid_attr() was implemented originally based on a draft of X/Open curses.