meson: cleanup common-user/ build

It is not necessary to have a separate static_library just for common_user
files; using the one that already covers the rest of common_ss is enough
unless you need to reuse some source files between emulators and tests.
Just place common files for all user-mode emulators in common_ss,
similar to what is already done for softmmu_ss in full system emulators.

The only disadvantage is that the include_directories under bsd-user/include/
and linux-user/include/ are now enabled for all targets rather than only
user mode emulators.  This however is not different from how include/sysemu/
is available when building user mode emulators.

Tested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

common-user/meson.build

@@ -1,6 +1,6 @@
 common_user_inc += include_directories('host/' / host_arch)
 
-common_user_ss.add(files(
+user_ss.add(files(
   'safe-syscall.S',
   'safe-syscall-error.c',
 ))

meson.build

@@ -2399,7 +2399,6 @@ blockdev_ss = ss.source_set()
 block_ss = ss.source_set()
 chardev_ss = ss.source_set()
 common_ss = ss.source_set()
-common_user_ss = ss.source_set()
 crypto_ss = ss.source_set()
 hwcore_ss = ss.source_set()
 io_ss = ss.source_set()
@@ -2651,17 +2650,6 @@ subdir('common-user')
 subdir('bsd-user')
 subdir('linux-user')
 
-common_user_ss = common_user_ss.apply(config_all, strict: false)
-common_user = static_library('common-user',
-                             sources: common_user_ss.sources(),
-                             dependencies: common_user_ss.dependencies(),
-                             include_directories: common_user_inc,
-                             name_suffix: 'fa',
-                             build_by_default: false)
-common_user = declare_dependency(link_with: common_user)
-
-user_ss.add(common_user)
-
 # needed for fuzzing binaries
 subdir('tests/qtest/libqos')
 subdir('tests/qtest/fuzz')
@@ -2879,6 +2867,7 @@ common_all = common_ss.apply(config_all, strict: false)
 common_all = static_library('common',
                             build_by_default: false,
                             sources: common_all.sources() + genh,
+                            include_directories: common_user_inc,
                             implicit_include_directories: false,
                             dependencies: common_all.dependencies(),
                             name_suffix: 'fa')