Fix cross-compilation by compiling zlib from source (#425)

install_ffmpeg.sh

@@ -42,9 +42,11 @@ if [[ "$BUILDARCH" == "amd64" && "$BUILDOS" == "linux" && "$GOARCH" == "arm64" &
   export STRIP="llvm-strip-14"
   export AR="llvm-ar-14"
   export RANLIB="llvm-ranlib-14"
+  export CFLAGS="--target=aarch64-linux-gnu"
+  export LDFLAGS="--target=aarch64-linux-gnu"
   EXTRA_CFLAGS="--target=aarch64-linux-gnu -I/usr/local/cuda_arm64/include $EXTRA_CFLAGS"
   EXTRA_LDFLAGS="-fuse-ld=lld --target=aarch64-linux-gnu -L/usr/local/cuda_arm64/lib64 $EXTRA_LDFLAGS"
-  EXTRA_FFMPEG_FLAGS="$EXTRA_FFMPEG_FLAGS --arch=aarch64 --enable-cross-compile --cc=clang --strip=llvm-strip-14"
+  EXTRA_FFMPEG_FLAGS="$EXTRA_FFMPEG_FLAGS --arch=aarch64 --enable-cross-compile --cc=clang-14 --strip=llvm-strip-14"
   HOST_OS="--host=aarch64-linux-gnu"
 fi
 
@@ -153,6 +155,16 @@ if [[ ! -e "$ROOT/x264" ]]; then
   make -j$NPROC install-lib-static
 fi
 
+if [[ ! -e "$ROOT/zlib-1.2.11" ]]; then
+  cd "$ROOT"
+  curl -o zlib-1.2.11.tar.gz https://zlib.net/fossils/zlib-1.2.11.tar.gz
+  tar xf zlib-1.2.11.tar.gz
+  cd zlib-1.2.11
+  ./configure --prefix="$ROOT/compiled" --static
+  make -j$NPROC
+  make -j$NPROC install
+fi
+
 if [[ "$GOOS" == "linux" && "$BUILD_TAGS" == *"debug-video"* ]]; then
   sudo apt-get install -y libnuma-dev cmake
   if [[ ! -e "$ROOT/x265" ]]; then