replace assert.h with cassert

The former was deprecated with C++14.

According to the C++11 and C++17 standards, both files are identical.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/command/CommandListBuilder.hxx

@@ -20,11 +20,10 @@
 #ifndef MPD_COMMAND_LIST_BUILDER_HXX
 #define MPD_COMMAND_LIST_BUILDER_HXX
 
+#include <cassert>
 #include <list>
 #include <string>
 
-#include <assert.h>
-
 class CommandListBuilder {
 	/**
 	 * print OK after each command execution