build with Meson instead of autotools

So long, autotools!  This is my last MPD related project to migrate
away from it.  It has its strengths, but also very obvious weaknesses
and weirdnesses.  Today, many of its quirks are not needed anymore,
and are cumbersome and slow.  Now welcome our new Meson overlords!

src/input/meson.build

@@ -0,0 +1,44 @@
+input_api = static_library(
+  'input_api',
+  'Error.cxx',
+  'InputStream.cxx',
+  'ThreadInputStream.cxx',
+  'AsyncInputStream.cxx',
+  'ProxyInputStream.cxx',
+  include_directories: inc,
+)
+
+input_api_dep = declare_dependency(
+  link_with: input_api,
+  dependencies: [
+    event_dep,
+  ],
+)
+
+subdir('plugins')
+
+input_glue = static_library(
+  'input_glue',
+  'Init.cxx',
+  'Registry.cxx',
+  'Open.cxx',
+  'LocalOpen.cxx',
+  'ScanTags.cxx',
+  'Reader.cxx',
+  'TextInputStream.cxx',
+  'ProxyInputStream.cxx',
+  'RewindInputStream.cxx',
+  'BufferedInputStream.cxx',
+  'MaybeBufferedInputStream.cxx',
+  include_directories: inc,
+)
+
+input_glue_dep = declare_dependency(
+  link_with: input_glue,
+  dependencies: [
+    input_plugins_dep,
+    fs_dep,
+    config_dep,
+    tag_dep,
+  ],
+)

src/input/plugins/meson.build

@@ -0,0 +1,110 @@
+input_plugins_sources = [
+  'FileInputPlugin.cxx',
+]
+
+if alsa_dep.found()
+  input_plugins_sources += 'AlsaInputPlugin.cxx'
+endif
+
+libcdio_paranoia_dep = dependency('libcdio_paranoia', version: '>= 0.4', required: get_option('cdio_paranoia'))
+conf.set('ENABLE_CDIO_PARANOIA', libcdio_paranoia_dep.found())
+if libcdio_paranoia_dep.found()
+  input_plugins_sources += 'CdioParanoiaInputPlugin.cxx'
+
+  conf.set('HAVE_CDIO_PARANOIA_PARANOIA_H',
+           compiler.has_header('cdio/paranoia/paranoia.h',
+                               dependencies: libcdio_paranoia_dep))
+endif
+
+if curl_dep.found()
+  input_plugins_sources += [
+    'CurlInputPlugin.cxx',
+    '../IcyInputStream.cxx',
+    '../../IcyMetaDataParser.cxx',
+  ]
+endif
+
+if ffmpeg_dep.found()
+  input_plugins_sources += 'FfmpegInputPlugin.cxx'
+endif
+
+libmms_dep = dependency('libmms', version: '>= 0.4', required: get_option('mms'))
+conf.set('ENABLE_MMS', libmms_dep.found())
+if libmms_dep.found()
+  input_plugins_sources += 'MmsInputPlugin.cxx'
+endif
+
+if nfs_dep.found()
+  input_plugins_sources += 'NfsInputPlugin.cxx'
+endif
+
+if smbclient_dep.found()
+  input_plugins_sources += 'SmbclientInputPlugin.cxx'
+endif
+
+qobuz_feature = get_option('qobuz')
+if qobuz_feature.disabled()
+  enable_qobuz = false
+else
+  enable_qobuz = curl_dep.found() and yajl_dep.found() and gcrypt_dep.found()
+  if not enable_qobuz and qobuz_feature.enabled()
+    error('Qobuz requires CURL, libyajl and libgcrypt')
+  endif
+endif
+conf.set('ENABLE_QOBUZ', enable_qobuz)
+if enable_qobuz
+  input_plugins_sources += [
+    'QobuzClient.cxx',
+    'QobuzErrorParser.cxx',
+    'QobuzLoginRequest.cxx',
+    'QobuzTrackRequest.cxx',
+    'QobuzTagScanner.cxx',
+    'QobuzInputPlugin.cxx',
+  ]
+endif
+
+tidal_feature = get_option('tidal')
+if tidal_feature.disabled()
+  enable_tidal = false
+else
+  enable_tidal = curl_dep.found() and yajl_dep.found()
+  if not enable_tidal and tidal_feature.enabled()
+    error('Tidal requires CURL and libyajl')
+  endif
+endif
+conf.set('ENABLE_TIDAL', enable_tidal)
+if enable_tidal
+  input_plugins_sources += [
+    'TidalErrorParser.cxx',
+    'TidalLoginRequest.cxx',
+    'TidalSessionManager.cxx',
+    'TidalTrackRequest.cxx',
+    'TidalTagScanner.cxx',
+    'TidalInputPlugin.cxx',
+  ]
+endif
+
+input_plugins = static_library(
+  'input_plugins',
+  input_plugins_sources,
+  include_directories: inc,
+  dependencies: [
+    alsa_dep,
+    curl_dep,
+    ffmpeg_dep,
+    libcdio_paranoia_dep,
+    libmms_dep,
+    nfs_dep,
+    smbclient_dep,
+    yajl_dep,
+    gcrypt_dep,
+  ],
+)
+
+input_plugins_dep = declare_dependency(
+  link_with: input_plugins,
+  dependencies: [
+    input_api_dep,
+    pcm_dep,
+  ],
+)