Adding the vcpkg integration files

Signed-off-by: Matthew A Johnson <matjoh@microsoft.com>

Author: matajoh

ports/snmalloc/portfile.cmake

@@ -0,0 +1,42 @@
+# Without static-shim: INTERFACE only — Release and Debug are identical.
+# With static-shim: compiled code is produced — both variants are needed.
+if(NOT "static-shim" IN_LIST FEATURES)
+    set(VCPKG_BUILD_TYPE release)
+endif()
+
+vcpkg_from_github(
+    OUT_SOURCE_PATH SOURCE_PATH
+    REPO microsoft/snmalloc
+    REF "v${VERSION}"
+    SHA512 0  # Placeholder: compute the real SHA512 from the GitHub release tarball before publishing to the vcpkg registry.
+    HEAD_REF main
+)
+
+vcpkg_check_features(OUT_FEATURE_OPTIONS FEATURE_OPTIONS
+    FEATURES
+        "static-shim" SNMALLOC_STATIC_LIBRARY
+    INVERTED_FEATURES
+        "static-shim" SNMALLOC_HEADER_ONLY_LIBRARY
+)
+
+vcpkg_cmake_configure(
+    SOURCE_PATH "${SOURCE_PATH}"
+    OPTIONS
+        -DSNMALLOC_BUILD_TESTING=OFF
+        ${FEATURE_OPTIONS}
+)
+
+vcpkg_cmake_install()
+
+vcpkg_cmake_config_fixup(
+    PACKAGE_NAME snmalloc
+    CONFIG_PATH share/snmalloc
+)
+
+file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/include")
+file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/share")
+
+vcpkg_install_copyright(FILE_LIST "${SOURCE_PATH}/LICENSE")
+
+file(INSTALL "${CMAKE_CURRENT_LIST_DIR}/usage"
+    DESTINATION "${CURRENT_PACKAGES_DIR}/share/${PORT}")

ports/snmalloc/usage

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+snmalloc provides CMake integration via:
+
+    find_package(snmalloc CONFIG REQUIRED)
+    target_link_libraries(<your-target> PRIVATE snmalloc::snmalloc)
+
+If installed with the "static-shim" feature, a compiled static library is also
+available that replaces malloc/free with a "sn_" prefix (e.g. sn_malloc, sn_free):
+
+    target_link_libraries(<your-target> PRIVATE snmalloc::snmallocshim-static)
+
+On non-Windows, the "static-shim" feature also installs shared library shims
+(snmalloc::snmallocshim, snmalloc::snmallocshim-checks, snmalloc::snmalloc-minimal)
+that can be used for LD_PRELOAD-based allocator replacement.

ports/snmalloc/vcpkg.json

@@ -0,0 +1,12 @@
+{
+    "name": "snmalloc",
+    "version-semver": "0.7.4",
+    "description": "A high-performance, message passing based allocator",
+    "homepage": "https://github.com/microsoft/snmalloc",
+    "license": "MIT",
+    "features": {
+        "static-shim": {
+            "description": "Build and install snmallocshim-static, a compiled static library that exports malloc/free with a configurable symbol prefix (default: sn_)"
+        }
+    }
+}

vcpkg.json

@@ -0,0 +1,12 @@
+{
+    "name": "snmalloc",
+    "version-semver": "0.7.4",
+    "description": "A high-performance, message passing based allocator",
+    "homepage": "https://github.com/microsoft/snmalloc",
+    "license": "MIT",
+    "features": {
+        "static-shim": {
+            "description": "Build and install snmallocshim-static, a compiled static library that exports malloc/free with a configurable symbol prefix (default: sn_)"
+        }
+    }
+}