build: Fix build errors on Windows

- Fix string no output variables on UWP

  On UWP, CMAKE_SYSTEM_PROCESSOR may be empty. As a result:
  string(TOLOWER ${CMAKE_SYSTEM_PROCESSOR} TARGET_ARCHITECTURE)
  will be treated as:
  string(TOLOWER TARGET_ARCHITECTURE)
  which, as a result, will cause a CMake error:

  CMake Error at CMakeLists.txt:42 (string):
    string no output variable specified

- Remove unnecessary header inclusions in uchardet.cpp

  These extra inclusions cause build errors on Windows.

CMakeLists.txt

@@ -39,7 +39,7 @@ if (BUILD_SHARED_LIBS)
 endif (BUILD_SHARED_LIBS)
 
 if (TARGET_ARCHITECTURE STREQUAL "")
-    string(TOLOWER ${CMAKE_SYSTEM_PROCESSOR} TARGET_ARCHITECTURE)
+    string(TOLOWER "${CMAKE_SYSTEM_PROCESSOR}" TARGET_ARCHITECTURE)
 endif (TARGET_ARCHITECTURE STREQUAL "")
 
 if (TARGET_ARCHITECTURE MATCHES ".*(x86)|(amd).*")

src/tools/uchardet.cpp

@@ -35,12 +35,9 @@
  *
  * ***** END LICENSE BLOCK ***** */
 #include "../uchardet.h"
-#include <cstdio>
-#include <cstring>
-#include <cstdlib>
 #include <getopt.h>
-#include <iostream>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #ifndef VERSION