clang-tidy: use C++ casting

[neheb]

Found with google-readability-casting

Signed-off-by: Rosen Penev [email protected]

[codecov]

Codecov Report

Merging #1664 (2dd9da0) into main (8dbc699) will increase coverage by 0.05%.
The diff coverage is 70.48%.

@@            Coverage Diff             @@
##             main    #1664      +/-   ##
==========================================
+ Coverage   66.89%   66.94%   +0.05%     
==========================================
  Files         151      151              
  Lines       20747    20746       -1     
==========================================
+ Hits        13879    13889      +10     
+ Misses       6868     6857      -11     

Impacted Files	Coverage Δ
samples/exiv2json.cpp	75.60% <0.00%> (ø)
samples/getopt-test.cpp	0.00% <0.00%> (ø)
samples/mmap-test.cpp	0.00% <0.00%> (ø)
src/canonmn_int.cpp	73.23% <ø> (ø)
src/casiomn_int.cpp	7.14% <0.00%> (ø)
src/cr2image.cpp	9.72% <0.00%> (+0.51%)	⬆️
src/http.cpp	0.00% <0.00%> (ø)
src/image_int.cpp	41.17% <0.00%> (ø)
src/ini.cpp	6.73% <0.00%> (+0.06%)	⬆️
src/xmpsidecar.cpp	85.00% <ø> (ø)
... and 31 more

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[piponazo]

LGTM, Thanks!