meson: rename libbasic to libbasic_static

Our variables for internal libraries are named 'libfoo' for the shared lib
variant, and 'libfoo_static' for the static lib variant. The only exception was
libbasic, because we didn't have a shared variant for it. But let's rename it
for consitency. This makes the build config easier to understand.

src/sysusers/meson.build

@@ -14,7 +14,7 @@ executables += [
                 'sources' : files('sysusers.c'),
                 'c_args' : '-DSTANDALONE',
                 'link_with' : [
-                        libbasic,
+                        libbasic_static,
                         libshared_static,
                         libsystemd_static,
                 ],