fix(sysdig): fix several compilation warnings

[hhoffstaette]

This fixes some inconsistencies that gcc-14 complains about:

• missing virtual default destructor in a base class
• potential use of uninitialised member variable
• mismatched type comparison (uint vs. int)

Nothing too critical, but why not. In detail:

/tmp/portage/dev-debug/sysdig-0.38.1-r1/work/sysdig-0.38.1/userspace/sinspui/cursescomponents.h:20:7: warning: 'class search_caller_interface' has virtual functions and accessible non-virtual destructor [-Wnon-virtual-dtor]
   20 | class search_caller_interface
      |       ^~~~~~~~~~~~~~~~~~~~~~~

/tmp/portage/dev-debug/sysdig-0.38.1-r1/work/sysdig-0.38.1/userspace/sinspui/cursescomponents.h:96:7: warning: 'ci.curses_table_column_info::m_size' may be used uninitialized [-Wmaybe-uninitialized]
   96 | class curses_table_column_info
      |       ^~~~~~~~~~~~~~~~~~~~~~~~

/tmp/portage/dev-debug/sysdig-0.38.1-r1/work/sysdig-0.38.1/userspace/sinspui/cursesui.cpp:2116:46: warning: comparison of integer expressions of different signedness: 'uint32_t' {aka 'unsigned int'} and 'int32_t' {aka 'int'} [-Wsign-compare]
 2116 |                 if(sinfo->m_prev_sorting_col != m_views.at(m_selected_view)->m_sortingcol)
      |                    ~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

There is a boatload more warnings wrt. potential string buffer overflows, but those are mostly harmless because the code is kind of weird & confuses gcc; unfortunately they are not easily fixed.

[hhoffstaette]

Apparently the CLA process requiring a sysdig-CLA-1.0-signed-off-by is no more, so I hope the regular S-o-b is OK.