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/libsystemd/meson.build

@@ -125,7 +125,7 @@ libsystemd_static = static_library(
         libsystemd_sources,
         include_directories : libsystemd_includes,
         c_args : libsystemd_c_args,
-        link_with : [libbasic],
+        link_with : [libbasic_static],
         dependencies : [threads,
                         libm,
                         librt,