cross compile insn, exclude x11 from headless

docs/CrossCompile.md

@@ -132,7 +132,9 @@ This is a guide for FreeBSD users mainly.
 
 Now you got a PowerPC sysroot - quickly decompress it somewhere, say `/home/user/opt/powerpc64le`. Create a toolchain file, for example `powerpc64le-toolchain.cmake`; always [consult the manual](https://man.freebsd.org/cgi/man.cgi?query=cmake-toolchains&sektion=7&manpath=FreeBSD+13.2-RELEASE+and+Ports).
 
-There is a script to automatically do all of this under `./tools/setup-cross-sysroot.sh`
+There is a script to automatically do all of this under `./tools/setup-cross-sysroot.sh`.
+
+Remember to add `-mabi=elfv1` to `CFLAGS`/`CXXFLAGS` otherwise the program will crash.
 
 Specify:
 

externals/ffmpeg/CMakeLists.txt

@@ -11,7 +11,7 @@ set(FFmpeg_HWACCEL_FLAGS)
 set(FFmpeg_HWACCEL_INCLUDE_DIRS)
 set(FFmpeg_HWACCEL_LDFLAGS)
 
-if (UNIX AND NOT ANDROID)
+if (PLATFORM_LINUX AND NOT ANDROID)
     find_package(PkgConfig REQUIRED)
     if (NOT ANDROID)
         pkg_check_modules(LIBVA libva)