tweaks: remove includes that appear to be superfluous

Without them, nano still compiles for me, with everything enabled,
even when using --enable-debug, --enable-utf8, and --with-slang.

src/browser.c

@@ -22,7 +22,6 @@
 #include "proto.h"
 
 #include <stdint.h>
-#include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>

src/color.c

@@ -21,7 +21,6 @@
 
 #include "proto.h"
 
-#include <stdio.h>
 #include <string.h>
 #include <errno.h>
 #include <unistd.h>

src/cut.c

@@ -23,7 +23,6 @@
 #include "proto.h"
 
 #include <string.h>
-#include <stdio.h>
 
 static bool keep_cutbuffer = FALSE;
 	/* Should we keep the contents of the cutbuffer? */

src/files.c

@@ -21,13 +21,10 @@
 
 #include "proto.h"
 
-#include <stdarg.h>
-#include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <errno.h>
-#include <ctype.h>
 #ifdef HAVE_PWD_H
 #include <pwd.h>
 #endif

src/global.c

@@ -24,7 +24,6 @@
 #include <ctype.h>
 #include <string.h>
 #include <strings.h>
-#include "assert.h"
 
 /* Global variables. */
 #ifndef NANO_TINY

src/help.c

@@ -22,9 +22,7 @@
 
 #include "proto.h"
 
-#include <stdio.h>
 #include <string.h>
-#include <ctype.h>
 #include <errno.h>
 
 #ifdef ENABLE_HELP

src/move.c

@@ -22,7 +22,6 @@
 #include "proto.h"
 
 #include <string.h>
-#include <ctype.h>
 
 /* Move to the first line of the file. */
 void do_first_line(void)

src/nano.c

@@ -22,14 +22,11 @@
 #include "proto.h"
 #include "revision.h"
 
-#include <stdio.h>
-#include <stdarg.h>
 #include <unistd.h>
 #include <string.h>
 #include <fcntl.h>
 #include <errno.h>
 #include <ctype.h>
-#include <locale.h>
 #ifdef ENABLE_UTF8
 #include <langinfo.h>
 #endif

src/prompt.c

@@ -21,8 +21,6 @@
 
 #include "proto.h"
 
-#include <stdio.h>
-#include <stdarg.h>
 #include <string.h>
 
 static char *prompt = NULL;

src/rcfile.c

@@ -23,9 +23,7 @@
 #include "proto.h"
 
 #include <glob.h>
-#include <stdarg.h>
 #include <string.h>
-#include <stdio.h>
 #include <errno.h>
 #include <unistd.h>
 #include <ctype.h>

src/search.c

@@ -22,11 +22,9 @@
 #include "proto.h"
 
 #include <string.h>
-#include <stdio.h>
-#include <unistd.h>
-#include <ctype.h>
-#include <errno.h>
+#ifdef DEBUG
 #include <time.h>
+#endif
 
 static bool came_full_circle = FALSE;
 	/* Have we reached the starting line again while searching? */

src/text.c

@@ -24,8 +24,6 @@
 
 #include "proto.h"
 
-#include <stdio.h>
-#include <signal.h>
 #include <unistd.h>
 #include <string.h>
 #include <fcntl.h>

src/utils.c

@@ -22,12 +22,10 @@
 #include "proto.h"
 
 #include <string.h>
-#include <stdio.h>
 #include <unistd.h>
 #ifdef HAVE_PWD_H
 #include <pwd.h>
 #endif
-#include <ctype.h>
 #include <errno.h>
 
 /* Return the user's home directory.  We use $HOME, and if that fails,

src/winio.c

@@ -26,10 +26,7 @@
 #include <sys/ioctl.h>
 #endif
 
-#include <stdio.h>
-#include <stdarg.h>
 #include <string.h>
-#include <unistd.h>
 #include <ctype.h>
 
 #ifdef REVISION