Add missing includes and external definitions

Several modules use std::array without including the
array header. Bad modules.

Some modules use STDOUT_FILENO and friends, or close()
without including unistd.h, where they are defined.

One module also uses WIFEXITED() without including
sys/wait.h.

Finally, environ is not specified to be defined in unistd.h. We
are required to define it ourselves according to POSIX, so let's
do that.

apt-pkg/contrib/strutl.cc

@@ -21,6 +21,7 @@
 #include <apt-pkg/fileutl.h>
 #include <apt-pkg/error.h>
 
+#include <array>
 #include <algorithm>
 #include <iomanip>
 #include <locale>

apt-pkg/deb/debindexfile.cc

@@ -30,6 +30,7 @@
 #include <sstream>
 
 #include <sys/stat.h>
+#include <unistd.h>
 									/*}}}*/
 
 // Sources Index							/*{{{*/

apt-pkg/deb/dpkgpm.cc

@@ -61,6 +61,8 @@
 #include <apti18n.h>
 									/*}}}*/
 
+extern char **environ;
+
 using namespace std;
 
 APT_PURE static string AptHistoryRequestingUser()			/*{{{*/

apt-pkg/edsp/edsplistparser.cc

@@ -21,6 +21,8 @@
 #include <apt-pkg/fileutl.h>
 #include <apt-pkg/pkgsystem.h>
 
+#include <array>
+
 									/*}}}*/
 
 // ListParser::edspListParser - Constructor				/*{{{*/

apt-private/private-show.cc

@@ -24,6 +24,7 @@
 #include <apt-private/private-show.h>
 
 #include <stdio.h>
+#include <unistd.h>
 #include <ostream>
 #include <string>
 

cmdline/apt-helper.cc

@@ -29,6 +29,7 @@
 #include <string>
 #include <vector>
 
+#include <unistd.h>
 #include <stdlib.h>
 
 #include <apti18n.h>

cmdline/apt-sortpkgs.cc

@@ -29,6 +29,7 @@
 #include <vector>
 #include <algorithm>
 #include <stdio.h>
+#include <unistd.h>
 #include <iostream>
 #include <string>
 #include <memory>

test/interactive-helper/test_fileutl.cc

@@ -4,6 +4,7 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <fcntl.h>