Add valgrind test targets about imageflow

[lilith]

Fix warnings from png encoding

[lilith]

What we used to do:

desc "run with valgrind"
valgrind_task("--leak-check=full --show-leak-kinds=all", :valgrind => PROFILING_PROGRAM)

desc "run with callgrind"
valgrind_task("--tool=callgrind --dump-instr=yes --cache-sim=yes --branch-sim=yes", :callgrind => PROFILING_PROGRAM)

desc "run with cachegrind"
task :cachegrind => PROFILING_PROGRAM do |t|
  cachegrind_out_file = "/tmp/cachegrind-out-file"
  with_ld_library_path('.') do
    sh "valgrind #{VALGRIND_OPTS} --tool=cachegrind --branch-sim=yes --cachegrind-out-file=#{cachegrind_out_file} ./#{t.prerequisites.first}"
  end
  sh "cg_annotate #{cachegrind_out_file}"
end

desc "build the test program"
file TEST_PROGRAM => TEST_OBJECTS + LIB_OBJECTS do |t|
  sh "#{CXX} -Werror #{t.prerequisites.join(" ")} -o #{t.name}"
end

desc "build the theft_test program"
file "theft_test" => THEFT_TEST_OBJECTS + LIB_OBJECTS do |t|
  sh "#{CXX} -Werror #{t.prerequisites.join(" ")} -ltheft -o #{t.name}"
end

task :test => TEST_PROGRAM do
  sh "./#{TEST_PROGRAM} #{ENV['ARGS']}"
end

desc "Run the test program with valgrind"
valgrind_task("--leak-check=full --show-leak-kinds=all --error-exitcode=2", :test_with_valgrind => TEST_PROGRAM)

desc "Run theft_test with valgrind"
valgrind_task("--leak-check=full --show-leak-kinds=all", :theft_test_with_valgrind => "theft_test")

[lilith]

This is now part of build.sh for both C and Rust. CI fails if any leaks or undefined behaviors are detected.