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

This reverts commit 6ed4aff4d3.  The
Meson wrap is broken on non-x86, because it unconditionally includes
<cpuid.h> which is an x86 only header.

meson.build

@@ -13,7 +13,6 @@ 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',
@@ -22,8 +21,6 @@ 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',