dest_rel_path is relative to header path
dest_rel_path
pub fn addInstallHeaderFile(b: *Build, source: LazyPath, dest_rel_path: []const u8) *Step.InstallFile
pub fn addInstallHeaderFile(b: *Build, source: LazyPath, dest_rel_path: []const u8) *Step.InstallFile { return b.addInstallFileWithDir(source, .header, dest_rel_path); }