title: strip command cannot be found by CMake Android toolchain for arm when running add_qt_android_apk
body: <p>In my CMake project I use the android.toolchain.cmake.</p>
  
  <p>I pass the following environment variables as defines:</p>
  
  <pre><code>export ANDROID_ABI="armeabi-v7a" # x86
  export ANDROID_TOOLCHAIN_NAME="arm-linux-androideabi-4.9" # "x86-4.9"
  export ANDROID_API_LEVEL="23"
  export QT_DIR="$HOME/Qt/5.7/android_armv7"
  export ANDROID_STANDALONE_TOOLCHAIN="$HOME/android-ndk-r12b/toolchains/arm-linux-androideabi-4.9/"
  export ANDROID_PREFIX="sdk-android-armv7" # sdk-android-x86
  export ANDROID_TARGET="armv7" # x86
  export QTAV_LIB_DIR="lib_android_arm" # lib_android_x86
  </code></pre>
  
  <p>I pass the variables the following way:</p>
  
  <pre><code>cmake -DUSE_COMPRESSED_FILES=1 -DJAVA_HOME="/usr/java/default/" -DANDROID_SDK="$ANDROID_HOME" -DQT_ANDROID_SDK_ROOT="$ANDROID_HOME" -DQT_ANDROID_ANT="$ANT_PATH" -DCMAKE_MODULE_PATH="../cmake" -DCMAKE_PREFIX_PATH="$QT_DIR/lib/cmake" -DCMAKE_TOOLCHAIN_FILE=../cmake/android.toolchain.cmake -DANDROID_NDK="$HOME/android-ndk-r12b" -DCMAKE_BUILD_TYPE=Debug -DANDROID_ABI="$ANDROID_ABI" -DANDROID_TOOLCHAIN_NAME="$ANDROID_TOOLCHAIN_NAME" -DANDROID_STANDALONE_TOOLCHAIN="$ANDROID_STANDALONE_TOOLCHAIN" -DANDROID_NATIVE_API_LEVEL="$ANDROID_API_LEVEL" -DQT_DIR="$QT_DIR" -DANDROID_PREFIX="$ANDROID_PREFIX" -DANDROID_TARGET="$ANDROID_TARGET" -DQTAV_LIB_DIR="$QTAV_LIB_DIR" ../
  
  cmake --build .
  </code></pre>
  
  <p>When "Stripping libraries to minimize size." it says:
  <code>Command does not exist: /home/peter/android-ndk-r12b/toolchains/armeabi-v7a-4.9/prebuilt/linux-x86_64/bin/arm-linux-androideabi-strip</code></p>
  
  <p>The path should be "arm-linux-androideabi-4.9" and not "armeabi-v7a-4.9". Why is the ANDROID_ABI used instead of the ANDROID_TOOLCHAIN_NAME?</p>
  
  <p>I do not have these problems for x86:</p>
  
  <pre><code>export ANDROID_ABI="x86"
  export ANDROID_TOOLCHAIN_NAME="x86-4.9"
  export ANDROID_API_LEVEL="23"
  export QT_DIR="$HOME/Qt5.7.0/5.7/android_x86"
  export ANDROID_STANDALONE_TOOLCHAIN="$HOME/android-ndk-r12b/toolchains/x86-4.9/"
  export ANDROID_PREFIX="sdk-android-x86"
  export ANDROID_TARGET="x86"
  export QTAV_LIB_DIR="lib_android_x86"
  </code></pre>
  
  <p>edit:
  The strip command is set by the android.toolchain.cmake file:</p>
  
  <pre><code> set( CMAKE_STRIP        "${ANDROID_TOOLCHAIN_ROOT}/bin/${ANDROID_TOOLCHAIN_MACHINE_NAME}-strip${TOOL_OS_SUFFIX}"   CACHE PATH "strip" )
  </code></pre>
  
  <p>ANDROID_TOOLCHAIN_ROOT is set this way since I specified a NDK path:</p>
  
  <pre><code># setup paths and STL for NDK
  if( BUILD_WITH_ANDROID_NDK )
   set( ANDROID_TOOLCHAIN_ROOT "${ANDROID_NDK_TOOLCHAINS_PATH}/${ANDROID_GCC_TOOLCHAIN_NAME}${ANDROID_NDK_TOOLCHAINS_SUBPATH}" )
  </code></pre>
  
  <p>so I guess ANDROID_GCC_TOOLCHAIN_NAME must be wrong? ANDROID_NDK_TOOLCHAINS_SUBPATH starts with "prebuilt" so it is correct. ANDROID_NDK_TOOLCHAINS_PATH ends with "toolchains" so it is correct, too.</p>
  
  <p>ANDROID_GCC_TOOLCHAIN_NAME is set if it is not Clang (which it is not):</p>
  
  <pre><code>set( ANDROID_GCC_TOOLCHAIN_NAME "${ANDROID_TOOLCHAIN_NAME}" )
  </code></pre>
  
  <p>so everything should work fine since my ANDROID_TOOLCHAIN_NAME has been specified as "arm-linux-androideabi-4.9" above but it does not.</p>
  
  <p>edit2:</p>
  
  <p>ANDROID_ABI is the value which is used instead. It is never used in any strip path as far as I can see it in the file "android.toolchain.cmake" but its value is copied to ANDROID_NDK_ABI_NAME as well which is neither used for any strip path.</p>
  
  <p>edit3:
  It might be an error in AddQtAndroidApk.cmake rather than the toolchain since the output is actually:</p>
  
  <pre><code>Stripping libraries to minimize size.
  Command does not exist: /home/peter/android-ndk-r12b/toolchains/armeabi-v7a-4.9/prebuilt/linux-x86_64/bin/arm-linux-androideabi-strip
  CMakeFiles/my_app_apk.dir/build.make:60: recipe for target 'run_android_deploy_qt' failed
  </code></pre>