[google-cloud-cpp] add missing subpackage

[coryan]

Add a missing vcpkg_cmake_config_fixup() for a

• What does your PR fix?

Fixes googleapis/google-cloud-cpp#8919

• Which triplets are supported/not supported? Have you updated the CI baseline?

N/A

• Does your PR follow the maintainer guide?

Yes

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

Yes.

Tested locally with vcpkg install google-cloud-cpp[core,storage]. Also tested with this Docker script:

FROM ubuntu:22.04

RUN apt-get update && \
    apt-get --no-install-recommends install -y apt-transport-https apt-utils \
        automake build-essential ca-certificates ccache cmake curl git \
        gcc g++ libc-ares-dev libc-ares2 libcurl4-openssl-dev libre2-dev \
        libssl-dev m4 make ninja-build pkg-config tar wget zlib1g-dev

RUN apt-get update && apt-get --no-install-recommends install -y zip unzip tar cmake ninja-build

WORKDIR /var/tmp/build/vcpkg
RUN curl -sSL https://github.com/coryan/vcpkg/archive/d6f0a18c632b73cb5ee2e44e5ee1079a4f5832b4.tar.gz | \
     tar -xzf - --strip-components=1

RUN ./bootstrap-vcpkg.sh
RUN ./vcpkg install google-cloud-cpp[core,storage]

WORKDIR /var/tmp/build/google-cloud-cpp
RUN curl -sSL https://github.com/googleapis/google-cloud-cpp/archive/refs/tags/v1.40.1.tar.gz | \
     tar -xzf - --strip-components=1

WORKDIR /var/tmp/build/google-cloud-cpp/google/cloud/storage/quickstart
RUN cmake -H. -B.build -DCMAKE_TOOLCHAIN_FILE=/var/tmp/build/vcpkg/scripts/buildsystems/vcpkg.cmake
RUN cmake --build .build

[BillyONeal]

Thanks for the patch!