encoding+lp: declare constexpr and noexcept where possible

Change-Id: Icf708af0b77d62d7d8e75527aaf51c7178e47125
diff --git a/src/encoding/block.cpp b/src/encoding/block.cpp
index ed8f5c9..639ed68 100644
--- a/src/encoding/block.cpp
+++ b/src/encoding/block.cpp
@@ -50,7 +50,7 @@
 }
 
 Block::Block(const EncodingBuffer& buffer)
-  : Block(const_cast<EncodingBuffer&>(buffer).getBuffer(), buffer.begin(), buffer.end(), true)
+  : Block(buffer.getBuffer(), buffer.begin(), buffer.end(), true)
 {
 }