Require POSIX.1 (1990) compliance on unix

Assume unix platforms support the original POSIX.1 standard.
Specifically, assume that if G_OS_UNIX, then we have chown(),
getcwd(), getgrgid(), getpwuid(), link(), <grp.h>, <pwd.h>,
<sys/types.h>, <sys/uio.h>, <sys/wait.h>, and <unistd.h>.

Additionally, since all versions of Windows that we care about also
have <sys/types.h>, we can remove HAVE_SYS_TYPES_H checks everywhere.

Also remove one include of <sys/times.h>, and the corresponding
configure check, since the include is not currently needed (and may
always have just been a typo for <sys/time.h>).

https://bugzilla.gnome.org/show_bug.cgi?id=710519

glib/gutils.c

@@ -29,6 +29,7 @@
  */
 
 #include "config.h"
+#include "glibconfig.h"
 
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
@@ -42,7 +43,7 @@
 #include <errno.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#ifdef HAVE_PWD_H
+#ifdef G_OS_UNIX
 #include <pwd.h>
 #endif
 #include <sys/types.h>
@@ -603,7 +604,7 @@ g_get_user_database_entry (void)
     {
       static UserDatabaseEntry e;
 
-#ifdef HAVE_PWD_H
+#ifdef G_OS_UNIX
       {
         struct passwd *pw = NULL;
         gpointer buffer = NULL;
@@ -718,7 +719,7 @@ g_get_user_database_entry (void)
         g_free (buffer);
       }
 
-#else /* !HAVE_PWD_H */
+#endif /* G_OS_UNIX */
 
 #ifdef G_OS_WIN32
       {
@@ -733,8 +734,6 @@ g_get_user_database_entry (void)
       }
 #endif /* G_OS_WIN32 */
 
-#endif /* !HAVE_PWD_H */
-
       if (!e.user_name)
         e.user_name = g_strdup ("somebody");
       if (!e.real_name)