chore(IWYU):Remove redundant includes (#4758)

test/format-impl-test.cc

@@ -13,7 +13,6 @@
 
 #include "fmt/format.h"
 #include "gmock/gmock.h"
-#include "util.h"
 
 using fmt::detail::bigint;
 using fmt::detail::fp;

test/posix-mock-test.cc

@@ -15,19 +15,19 @@
 #include <errno.h>
 #include <fcntl.h>
 
-#include <climits>
 #include <memory>
 
 #include "../src/os.cc"
 
 #ifdef _WIN32
 #  include <io.h>
+
+#  include <climits>  // UINT_MAX
 #  undef max
 #endif
 
 #include "gmock/gmock.h"
 #include "gtest-extra.h"
-#include "util.h"
 
 using fmt::buffered_file;