util/ByteOrder: add FromLE16S()

src/util/ByteOrder.hxx

@@ -243,4 +243,15 @@ ToLE64(uint64_t value) noexcept
 	return IsLittleEndian() ? value : ByteSwap64(value);
 }
 
+/**
+ * Converts a 16 bit integer from little endian to the host byte order
+ * and returns it as a signed integer.
+ */
+constexpr int16_t
+FromLE16S(uint16_t value) noexcept
+{
+	/* assuming two's complement representation */
+	return static_cast<int16_t>(FromLE16(value));
+}
+
 #endif