如何为Android编译libgit2？编译报错求助

背景 #

开发一款基于libgit2的Flutter应用，Linux环境下编译libgit2无问题。现在需要添加Android支持，使用Android NDK（r26及以下），配置的toolchain.cmake如下：

set(CMAKE_SYSTEM_NAME Android)
set(CMAKE_SYSTEM_VERSION 34)

set(CMAKE_ANDROID_ARCH_ABI arm64-v8a)
set(CMAKE_ANDROID_NDK /opt/android-ndk)

set(OPENSSL_INCLUDE_DIR "/实际路径/openssl/include")
set(OPENSSL_CRYPTO_LIBRARY "/实际路径/openssl/libcrypto.so")
set(OPENSSL_SSL_LIBRARY "/实际路径/openssl/libssl.so")

注：配置中已使用OpenSSL仓库的实际路径，而非示例中的/path/to/openssl；用NDK编译OpenSSL无问题。

问题1：NDK r26下CMake无法通过编译器测试 #

使用上述配置编译libgit2时，CMake报错：

CMake Error at /usr/share/cmake/Modules/CMakeTestCCompiler.cmake:67 (message):
  The C compiler

    "/opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang"

  is not able to compile a simple test program.

发现/opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang是指向clang-17的文本文件，尝试在toolchain中手动指定编译器路径但无效：

set(CMAKE_C_COMPILER   /opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang-17)
set(CMAKE_CXX_COMPILER /opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang-17)

将该文本文件替换为软链接后，出现新错误：

CMake Error at /usr/share/cmake/Modules/CMakeTestCCompiler.cmake:67 (message):
  The C compiler

    "/opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang"

  is not able to compile a simple test program.

  It fails with the following output:

    Change Dir: '/home/jakub/Projekty/dpc/lib/libgit/build/arm64/CMakeFiles/CMakeScratch/TryCompile-03LVGf'
    
    Run Build Command(s): /usr/bin/cmake -E env VERBOSE=1 /usr/bin/gmake -f Makefile cmTC_f226c/fast
    /usr/bin/gmake  -f CMakeFiles/cmTC_f226c.dir/build.make CMakeFiles/cmTC_f226c.dir/build
    gmake[1]: Vstupuje se do adresáře „/media/data/Všechny Projekty/dpc/lib/libgit/build/arm64/CMakeFiles/CMakeScratch/TryCompile-03LVGf“
    Building C object CMakeFiles/cmTC_f226c.dir/testCCompiler.c.o
    /opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang --target=aarch64-none-linux-android34   -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -fexceptions  -O2 -g -DNDEBUG -MD -MT CMakeFiles/cmTC_f226c.dir/testCCompiler.c.o -MF CMakeFiles/cmTC_f226c.dir/testCCompiler.c.o.d -o CMakeFiles/cmTC_f226c.dir/testCCompiler.c.o -c /home/jakub/Projekty/dpc/lib/libgit/build/arm64/CMakeFiles/CMakeScratch/TryCompile-03LVGf/testCCompiler.c
    Linking C executable cmTC_f226c
    /usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_f226c.dir/link.txt --verbose=1
    /opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang --target=aarch64-none-linux-android34 -DANDROID -fdata-sections -ffunction-sections -funwind-tables -fstack-protector-strong -no-canonical-prefixes -D_FORTIFY_SOURCE=2 -Wformat -Werror=format-security -fexceptions  -O2 -g -DNDEBUG -Wl,--build-id=sha1 -Wl,--no-undefined-version -Wl,--fatal-warnings -Wl,--gc-sections -Qunused-arguments -Wl,--no-undefined  -Wl,--gc-sections  CMakeFiles/cmTC_f226c.dir/testCCompiler.c.o -o cmTC_f226c   -latomic -lm 
    clang: error: unable to execute command: posix_spawn failed: Exec format error
    clang: error: linker command failed with exit code 1 (use -v to see invocation)

执行/opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin/clang --version输出：

Android (10087095, +pgo, +bolt, +lto, -mlgo, based on r487747c) clang version 17.0.2 (https://android.googlesource.com/toolchain/llvm-project d9f89f4d16663d5012e5c09495f3b30ece3d2362)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/android-ndk/toolchains/llvm/prebuilt/linux-x86_64/bin

问题2：NDK r22b下出现头文件编译错误 #

尝试使用NDK r22b（或更早版本）时，配置可完成且接近编译完成，但出现头文件错误，无法识别inline关键字：

/opt/android-ndk-r22/toolchains/llvm/prebuilt/linux-x86_64/bin/../sysroot/usr/include/linux/swab.h:40:8: error: unknown type name 'inline'
static inline __attribute__((__const__)) __u32 __fswahw32(__u32 val) {
       ^
/opt/android-ndk-r22/toolchains/llvm/prebuilt/linux-x86_64/bin/../sysroot/usr/include/linux/swab.h:40:47: error: expected ';' after top level declarator
static inline __attribute__((__const__)) __u32 __fswahw32(__u32 val) {

寻求相关技术解决方案。

内容的提问来源于stack exchange，提问作者Jakub Slabý