title: CMake: remove a compile flag from CMAKE_C_FLAGS_RELEASE only for a specific target
body: <p>I have</p>
  <pre><code>set(CMAKE_CXX_FLAGS_RELEASE &quot;-O3 -m64 -march=native -flto&quot;)
  </code></pre>
  <p>but I'd like to remove <code>-flto</code> for a specific target compilation:</p>
  <pre><code>file(GLOB TST_SOURCES &quot;${CMAKE_SOURCE_DIR}/x64_test/*.cpp&quot;)
  add_executable(_x64_test ${TST_SOURCES})
  target_compile_options(_x64_test PRIVATE -Wall -DLITTLE_ENDIAN)
  target_link_libraries(_x64_test PRIVATE test_iface pthread m)
  </code></pre>
  <p>Is it possible?</p>