misc fixes:

  * add appveyor.yml file to Makefile
  * add missing android.cmake file (from webmproject#107)

Change-Id: Idd5b816f76a0f5eae0e4640c64cc58c7f8195143

Makefile

@@ -176,6 +176,7 @@ DIST_FILES= \
          cmake/android.cmake \
          cmake/cpu.cmake \
          cmake/sjpegConfig.cmake.in \
+         appveyor.yml \
          src/libsjpeg.pc.in \
          src/bit_writer.cc  \
          src/bit_writer.h  \

cmake/android.cmake

@@ -0,0 +1,52 @@
+# Copyright 2021 Google LLC.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Configuration for Android build
+
+if(SJPEG_CMAKE_TOOLCHAINS_ANDROID_CMAKE_)
+  return()
+endif() # SJPEG_CMAKE_TOOLCHAINS_ANDROID_CMAKE_
+
+if(NOT ANDROID_PLATFORM)
+  set(ANDROID_PLATFORM android-22)
+endif()
+
+# Choose target architecture with:
+#
+#  -DANDROID_ABI={armeabi-v7a,armeabi-v7a with NEON,arm64-v8a,x86,x86_64}
+if(NOT ANDROID_ABI)
+  set(ANDROID_ABI arm64-v8a)
+endif()
+
+# Force arm mode for 32-bit targets (instead of the default thumb) to improve
+# performance.
+if(NOT ANDROID_ARM_MODE)
+  set(ANDROID_ARM_MODE arm)
+endif()
+
+# Toolchain files don't have access to cached variables:
+# https://gitlab.kitware.com/cmake/cmake/issues/16170. Set an intermediate
+# environment variable when loaded the first time.
+if(SJPEG_ANDROID_NDK_PATH)
+  set(ENV{SJPEG_ANDROID_NDK_PATH} "${SJPEG_ANDROID_NDK_PATH}")
+else()
+  set(SJPEG_ANDROID_NDK_PATH "$ENV{SJPEG_ANDROID_NDK_PATH}")
+endif()
+
+if(NOT SJPEG_ANDROID_NDK_PATH)
+  message(FATAL_ERROR "\nSJPEG_ANDROID_NDK_PATH not set.\n"
+                      "Try using \$NDK_ROOT?\n")
+endif()
+
+include("${SJPEG_ANDROID_NDK_PATH}/build/cmake/android.toolchain.cmake")