Make local includes consistent; use double quotes for local includes

except for generated ones where we use angle brackets.
Also g/c unused compat.h.

src/error.c

@@ -23,7 +23,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include <missing.h>
+#include "missing.h"
 #include "error.h"
 
 static void _warning(int, const char *, va_list);

src/sesh.c

@@ -27,7 +27,7 @@
 #include <string.h>
 #include <unistd.h>
 
-#include <missing.h>
+#include "missing.h"
 
 int
 main (int argc, char *argv[])

src/sudo.h

@@ -24,14 +24,14 @@
 #ifndef _SUDO_SUDO_H
 #define _SUDO_SUDO_H
 
-#include <pathnames.h>
 #include <limits.h>
 
-#include <missing.h>
-#include <alloc.h>
-#include <error.h>
-#include <fileops.h>
-#include <list.h>
+#include <pathnames.h>
+#include "missing.h"
+#include "alloc.h"
+#include "error.h"
+#include "fileops.h"
+#include "list.h"
 
 #ifdef __TANDEM
 # define ROOT_UID       65535

src/sudo_noexec.c

@@ -24,7 +24,7 @@
 #endif
 #include <stdarg.h>
 
-#include <missing.h>
+#include "missing.h"
 
 /*
  * Dummy versions of the execve() family of syscalls.  We don't need

src/ttysize.c

@@ -34,7 +34,7 @@
 #endif /* HAVE_UNISTD_H */
 #include <termios.h>
 
-#include <missing.h>
+#include "missing.h"
 
 #if !defined(TIOCGSIZE) && defined(TIOCGWINSZ)
 # define TIOCGSIZE	TIOCGWINSZ