python/build/libs.py: remove flac, switch to Meson wrap

meson.build

@@ -13,6 +13,7 @@ project(
     # If we build those libraries as Meson subproject, they shall be
     # linked statically into the MPD executable.
     'expat:default_library=static',
+    'flac:default_library=static',
     'fmt:default_library=static',
     'gtest:default_library=static',
     'sqlite3:default_library=static',
@@ -21,6 +22,8 @@ project(
     # Not interested in compiler warnings from subprojects.
     'expat:werror=false',
     'expat:warning_level=0',
+    'flac:werror=false',
+    'flac:warning_level=0',
     'fmt:warning_level=0',
     'gtest:warning_level=0',
     'sqlite3:warning_level=0',