[build] Inline lz4 submodule into src-ThirdParty/

.github/dependabot.yml

@@ -54,6 +54,5 @@ updates:
       interval: "daily"
     ignore:
       - dependency-name: "external/constexpr-xxh3"
-      - dependency-name: "external/lz4"
       - dependency-name: "external/robin-map"
       - dependency-name: "external/xxHash"

.github/skills/update-tpn/SKILL.md

@@ -56,7 +56,6 @@ Read `.gitmodules` for all submodules. Current submodules and their license file
 | Submodule | URL | License File |
 |-----------|-----|-------------|
 | Java.Interop | https://github.com/dotnet/java-interop | `external/Java.Interop/LICENSE` |
-| lz4 | https://github.com/dotnet/lz4 (fork of https://github.com/lz4/lz4) | `external/lz4/lib/LICENSE` |
 | xxHash | https://github.com/Cyan4973/xxHash | `external/xxHash/LICENSE` |
 | constexpr-xxh3 | https://github.com/chys87/constexpr-xxh3 | `external/constexpr-xxh3/LICENSE` |
 | robin-map | https://github.com/xamarin/robin-map (fork of https://github.com/Tessil/robin-map) | `external/robin-map/LICENSE` |
@@ -74,6 +73,7 @@ List contents of `src-ThirdParty/` directory. Current vendored code and license
 | `bazel/` | bazelbuild/bazel | https://github.com/bazelbuild/bazel/ (Apache 2.0) |
 | `bionic/` | google/bionic | https://android.googlesource.com/platform/bionic/ (Apache 2.0) |
 | `crc32.net/` | force-net/crc32.net | https://github.com/force-net/Crc32.NET (MIT) |
+| `lz4/` | lz4/lz4 | https://github.com/lz4/lz4 (BSD-2-Clause; license header in `src-ThirdParty/lz4/lz4.c`) |
 | `NUnitLite/` | nunit/nunitlite | https://github.com/nunit/nunitlite/ (MIT) |
 | `StrongNameSigner/` | brutaldev/StrongNameSigner | https://github.com/brutaldev/StrongNameSigner/ (Apache 2.0) |
 
@@ -103,7 +103,7 @@ The `src/Xamarin.Android.Build.Tasks/Linker/External/` directory contains vendor
 | Linker/External/ | mono/linker | https://github.com/mono/linker/ (MIT) |
 
 #### Native Libraries (from CMakeLists.txt)
-Check `src/native/` CMakeLists.txt files for references to external native code. The submodules above (lz4, xxHash, libunwind, robin-map) are compiled into native libraries.
+Check `src/native/` CMakeLists.txt files for references to external native code. The submodules above (xxHash, libunwind, robin-map) and the vendored `src-ThirdParty/lz4/` source are compiled into native libraries.
 
 #### Android SDK Tools
 These are downloaded and shipped with the SDK:

.gitmodules

@@ -18,10 +18,6 @@
     path = external/libunwind
     url = https://github.com/libunwind/libunwind.git
     branch = v1.8-stable
-[submodule "external/lz4"]
-    path = external/lz4
-    url = https://github.com/dotnet/lz4
-    branch = release
 [submodule "external/robin-map"]
     path = external/robin-map
     url = https://github.com/xamarin/robin-map

.lgtm.yml

@@ -1,6 +1,2 @@
 queries:
   - exclude: cs/campaign/constantine
-paths:
-  exclude:
-    # we don't ship lz4 tests
-    - external/lz4/tests

Configuration.props

@@ -99,7 +99,7 @@
     <SqliteSourceDirectory Condition=" '$(SqliteSourceDirectory)' == '' ">$(MSBuildThisFileDirectory)external\sqlite</SqliteSourceDirectory>
     <LibUnwindSourceDirectory Condition=" '$(LibUnwindSourceDirectory)' == '' ">$(MSBuildThisFileDirectory)external\libunwind</LibUnwindSourceDirectory>
     <LibUnwindGeneratedHeadersDirectory Condition=" '$(LibUnwindGeneratedHeadersDirectory)' == '' ">$(BootstrapOutputDirectory)\libunwind</LibUnwindGeneratedHeadersDirectory>
-    <LZ4SourceDirectory Condition=" '$(LZ4SourceDirectory)' == '' ">$(MSBuildThisFileDirectory)external\lz4</LZ4SourceDirectory>
+    <LZ4SourceDirectory Condition=" '$(LZ4SourceDirectory)' == '' ">$(MSBuildThisFileDirectory)src-ThirdParty\lz4</LZ4SourceDirectory>
     <XamarinAndroidSourcePath>$(MSBuildThisFileDirectory)</XamarinAndroidSourcePath>
     <ThirdPartySourcePath>$(MSBuildThisFileDirectory)src-ThirdParty\</ThirdPartySourcePath>
     <AllSupported32BitTargetAndroidAbis>armeabi-v7a;x86</AllSupported32BitTargetAndroidAbis>