pkgconf-pc-version: gate on glibc, not just linux
The test was enabled on android-prebuilt targets (isLinux && !isMusl && !isStatic), where it tried to build systemd for a bionic libc target and failed with a dependency error. systemd only builds on glibc, so gate the systemd module set on hostPlatform.libc == "glibc" (excludes android/bionic, musl, Windows, wasm) plus !isStatic.