[DirectoryWatcher] Include limits.h instead of MathExtras.h (NFC)

Author: kazutakahirata

clang/lib/DirectoryWatcher/linux/DirectoryWatcher-linux.cpp

@@ -14,7 +14,6 @@
 #include "llvm/Support/AlignOf.h"
 #include "llvm/Support/Errno.h"
 #include "llvm/Support/Error.h"
-#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Path.h"
 #include <atomic>
 #include <condition_variable>
@@ -25,6 +24,7 @@
 #include <vector>
 
 #include <fcntl.h>
+#include <limits.h>
 #include <optional>
 #include <sys/epoll.h>
 #include <sys/inotify.h>