Rename an identifier of ours called stdout

This is a reserved identifier on NetBSD --- it is replaced by a macro on
that platform --- and so we cannot use it.

src/libmain/shared.cc

@@ -379,9 +379,9 @@ RunPager::RunPager()
     });
 
     pid.setKillSignal(SIGINT);
-    stdout = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 0);
+    std_out = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 0);
     if (dup2(toPager.writeSide.get(), STDOUT_FILENO) == -1)
-        throw SysError("dupping stdout");
+        throw SysError("dupping standard output");
 }
 
 
@@ -390,7 +390,7 @@ RunPager::~RunPager()
     try {
         if (pid != -1) {
             std::cout.flush();
-            dup2(stdout, STDOUT_FILENO);
+            dup2(std_out, STDOUT_FILENO);
             pid.wait();
         }
     } catch (...) {

src/libmain/shared.hh

@@ -85,8 +85,9 @@ struct LegacyArgs : public MixCommonArgs
 void showManPage(const std::string & name);
 
 /**
- * The constructor of this class starts a pager if stdout is a
- * terminal and $PAGER is set. Stdout is redirected to the pager.
+ * The constructor of this class starts a pager if standard output is a
+ * terminal and $PAGER is set. Standard output is redirected to the
+ * pager.
  */
 class RunPager
 {
@@ -96,7 +97,7 @@ public:
 
 private:
     Pid pid;
-    int stdout;
+    int std_out;
 };
 
 extern volatile ::sig_atomic_t blockInt;