Do not allow zero-length reads

Since this may create pretty odd issues, since reading 0 bytes will
return 0, and some code may not be ready for this.

v0: add a check in ReadBuffer ctor
v2: Do not create empty ReadBuffer from BufferWithOwnMemory with empty size
v3:
- revert "Do not create empty ReadBuffer from BufferWithOwnMemory with empty size"
- Replace INVALID_SETTING_VALUE with LOGICAL_ERROR
- Move the check for empty buffer in ReadBuffer into reading because of MMapReadBufferFromFile
v4: replace with assert of internal_buffer.size()
v5: move assertion to implementations since there are exceptions for
    nested readers, like LimitReadBuffer and similar.

src/IO/ReadBufferFromFileDescriptor.cpp

@@ -51,6 +51,9 @@ std::string ReadBufferFromFileDescriptor::getFileName() const
 
 bool ReadBufferFromFileDescriptor::nextImpl()
 {
+    /// If internal_buffer size is empty, then read() cannot be distinguished from EOF
+    assert(!internal_buffer.empty());
+
     size_t bytes_read = 0;
     while (!bytes_read)
     {

src/IO/SynchronousReader.cpp

@@ -37,6 +37,9 @@ namespace ErrorCodes
 
 std::future<IAsynchronousReader::Result> SynchronousReader::submit(Request request)
 {
+    /// If size is zero, then read() cannot be distinguished from EOF
+    assert(request.size);
+
     int fd = assert_cast<const LocalFileDescriptor &>(*request.descriptor).fd;
 
 #if defined(POSIX_FADV_WILLNEED)

src/IO/ThreadPoolReader.cpp

@@ -76,6 +76,9 @@ ThreadPoolReader::ThreadPoolReader(size_t pool_size, size_t queue_size_)
 
 std::future<IAsynchronousReader::Result> ThreadPoolReader::submit(Request request)
 {
+    /// If size is zero, then read() cannot be distinguished from EOF
+    assert(request.size);
+
     int fd = assert_cast<const LocalFileDescriptor &>(*request.descriptor).fd;
 
 #if defined(__linux__)