Fix various warnings ubuntu12.04

[fspindle]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 77.01149% with 20 lines in your changes are missing coverage. Please review.

Project coverage is 52.68%. Comparing base (7328caa) to head (0a7d3f3).

Files	Patch %	Lines
modules/core/src/image/vpImageCircle.cpp	0.00%	9 Missing ⚠️
modules/imgproc/src/vpImgproc.cpp	12.50%	7 Missing ⚠️
...odules/tracker/me/src/moving-edges/vpMeEllipse.cpp	88.88%	2 Missing ⚠️
modules/core/include/visp3/core/vpImageFilter.h	66.66%	1 Missing ⚠️
modules/core/src/image/vpImageFilter.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1348      +/-   ##
==========================================
+ Coverage   52.66%   52.68%   +0.02%     
==========================================
  Files         410      410              
  Lines       52646    52676      +30     
==========================================
+ Hits        27724    27753      +29     
- Misses      24922    24923       +1     

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