SPECS: tinysparql: Align libstemmer and completion dependencies

[Jingwiw]

Changes

• Add the missing remote asset checksum for the tinysparql source archive.

• Give the existing libstemmer build condition an explicit default.

  Upstream defaults stemmer support to auto, and the spec already has conditional logic around stemmer. Setting the bcond default keeps the package's default build state explicit instead of letting the buildroot decide it.

  Source: meson_options.txt

  option('stemmer', type: 'feature', value: 'auto',
         description: 'Stemming words while indexing')

  Source: meson.build

  libstemmer = cc.find_library('stemmer', required: get_option('stemmer'))
  if not libstemmer.found()
    subproject('libstemmer')
    libstemmer = dependency('libstemmer', required: true)
  endif

• Add pkgconfig(bash-completion) for the enabled bash completion install path.

  Bash completion installation is enabled by default, and Meson uses the bash-completion pkg-config file to get the packaged completionsdir.

  Source: meson_options.txt

  option('bash_completion', type: 'boolean', value: true,
         description: 'Whether to install Bash completion files')
  option('bash_completion_dir', type: 'string',
         description: 'Directory to install Bash completion files')

  Source: meson.build

  if get_option('bash_completion')
    bash_completion_dir = get_option('bash_completion_dir')
  
    if bash_completion_dir == ''
      bash_completion_package = dependency('bash-completion', required: false)
      if bash_completion_package.found()
        bash_completion_dir = bash_completion_package.get_variable(pkgconfig: 'completionsdir',
                                                                   pkgconfig_define: [ 'prefix', get_option('prefix') ])
      else
        bash_completion_dir = join_paths(datadir, 'bash-completion', 'completions')
      endif

  Source: src/cli/meson.build

  if get_option('bash_completion')
      install_data(
          sources: 'bash-completion/tinysparql',
          install_dir: bash_completion_dir,
          rename: main_command_name)
  endif

• Use %autochangelog directly, matching the current spec style.

AIGC Declaration: CodeX with gpt5.5 was used as coding agent.

Signed-off-by: Jingwiw wangjingwei@iscas.ac.cn