meson: fix libcommon being publicly exposed as a static link dependency

libcommon isn't even installed, so that means libalpm.a (if installed)
is fatally broken as it misses objects. The problem is that meson
doesn't handle this case correctly:

mesonbuild/meson#3934
mesonbuild/meson#3937
mesonbuild/meson#3939

Work around this by manually extracting libcommon's .o files into the
list of objects used to create libalpm.

meson.build

@@ -317,9 +317,10 @@ libcommon = static_library(
 libalpm_a = static_library(
   'alpm',
   libalpm_sources,
+  # https://github.com/mesonbuild/meson/issues/3937
+  objects : libcommon.extract_all_objects(),
   include_directories : includes,
   dependencies : [crypto_provider, libarchive, libcurl, gpgme],
-  link_with : [libcommon],
   install : true)
 
 if get_option('default_library') != 'static'
@@ -336,7 +337,6 @@ install_headers(
   'lib/libalpm/alpm.h',
   'lib/libalpm/alpm_list.h')
 
-# TODO: libs.private seem quite wrong here
 pkgconfig = import('pkgconfig')
 pkgconfig.generate(
   libalpm,