Small fixes to the cross-compiling scripts (#38)

build-aarch64-linux-gnu.sh

@@ -1,5 +1,13 @@
 #!/usr/bin/env bash
 
+if ! command -v aarch64-linux-gnu-gcc  &> /dev/null; then
+  echo "Please install a toolchain for cross-compiling."
+  echo "You can refer to: "
+  echo "  https://k2-fsa.github.io/sherpa/ncnn/install/aarch64-embedded-linux.html"
+  echo "for help."
+  exit 1
+fi
+
 set -x
 
 dir=build-aarch64-linux-gnu

build-android-arm64-v8a-with-vulkan.sh

@@ -82,7 +82,7 @@ if [ ! -e my-glslang/build/install/lib/libglslang.so ]; then
     exit 1
   fi
 
-  cmake $SOURCE_DIR \
+  cmake \
     -DBUILD_SHARED_LIBS=ON \
     -DCMAKE_INSTALL_PREFIX="$(pwd)/install" \
     -DANDROID_ABI=arm64-v8a \

build-arm-linux-gnueabihf.sh

@@ -1,6 +1,14 @@
 #!/usr/bin/env bash
 
-set -x
+if ! command -v arm-linux-gnueabihf-gcc  &> /dev/null; then
+  echo "Please install a toolchain for cross-compiling."
+  echo "You can refer to: "
+  echo "  https://k2-fsa.github.io/sherpa/ncnn/install/arm-embedded-linux.html"
+  echo "for help."
+  exit 1
+fi
+
+set -ex
 
 dir=build-arm-linux-gnueabihf
 mkdir -p $dir
@@ -10,5 +18,6 @@ cmake \
   -DCMAKE_BUILD_TYPE=Release \
   -DCMAKE_TOOLCHAIN_FILE=../toolchains/arm-linux-gnueabihf.toolchain.cmake \
   ..
+
 make VERBOSE=1 -j4
 make install/strip