fix(sysdig): fix several compilation warnings

This fixes some inconsistencies that gcc-14 complains about:
- mismatched type comparison (uint vs. int)
- missing virtual default destructor in a base class
- potential use of uninitialised member variable

Signed-off-by: Holger Hoffstätte <holger@applied-asynchrony.com>

userspace/chisel/chisel_viewinfo.h

@@ -176,7 +176,7 @@ class chisel_view_info
 	std::string m_description;
 	std::vector<std::string> m_tags;
 	std::vector<std::string> m_tips;
-	int32_t m_sortingcol;
+	uint32_t m_sortingcol;
 	std::vector<std::string> m_applies_to;
 	std::vector<chisel_view_column_info> m_columns;
 	bool m_use_defaults;

userspace/sinspui/cursescomponents.h

@@ -23,6 +23,7 @@ class search_caller_interface
 	virtual bool on_search_key_pressed(std::string search_str) = 0;
 	virtual bool on_search_next() = 0;
 	virtual std::string* get_last_search_string() = 0;
+	virtual ~search_caller_interface() = default;
 };
 
 class sidemenu_list_entry
@@ -97,6 +98,7 @@ class curses_table_column_info
 public:	
 	curses_table_column_info()
 	{
+		m_size = -1;
 	}
 
 	//