Fix includes for IWYU

uci.cpp should remove these lines:
- #include <cstdint>

external/zip.h should add these lines:

external/zip.cpp should add these lines:

src/external/zip.cpp

@@ -10,6 +10,8 @@
 #define __STDC_WANT_LIB_EXT1__ 1
 
 #include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
 #include <sys/stat.h>
 #include <time.h>
 

src/external/zip.h

@@ -16,6 +16,10 @@
     #include <string.h>
     #include <sys/types.h>
 
+    #ifdef __linux__
+        #include <features.h>
+    #endif
+
     #ifndef ZIP_SHARED
         #define ZIP_EXPORT
     #else

src/uci.cpp

@@ -21,7 +21,6 @@
 #include <algorithm>
 #include <cassert>
 #include <cmath>
-#include <cstdint>
 #include <cstdlib>
 #include <deque>
 #include <iostream>