title: FindPkgConfig with set_target_properties is unusable for setting CFLAGS/LDFLAGS
body: <p><code>pkg_check_modules</code> from FindPkgConfig gives <code>MYLIBRARY_LDFLAGS</code> and <code>MYLIBRARY_CFLAGS</code> that are ordinary CMake lists (with semicolon-separator).</p>
  
  <p>The <code>set_target_properties</code> and <code>set_property</code> accept just one string.</p>
  
  <p>So that doesn't work because it doesn't expand the list:</p>
  
  <pre><code>set_property(TARGET ${PROJECT_NAME} APPEND PROPERTY LINK_FLAGS ${MYLIBRARY_LDFLAGS})
  </code></pre>
  
  <p>This gives same thing with the semicolons inside:</p>
  
  <pre><code>set_property(TARGET ${PROJECT_NAME} APPEND PROPERTY LINK_FLAGS "${MYLIBRARY_LDFLAGS}")
  </code></pre>
  
  <p><code>set_target_properties</code> expands into multiple strings when unquoted and into one string with semicolons when quoted.</p>
  
  <p>How am I supposed to use that?</p>