Update android_make to support both --gcc and --clang options.

platform_tools/android/bin/utils/setup_toolchain.sh

 # Copyright 2015 Google Inc.
 #
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 #!/bin/bash
 #
 # setup_toolchain.sh: Sets toolchain environment variables used by other scripts.
 
 # Fail-fast if anything in the script fails.
@@ skipping 81 matching lines @@
 # Cross compiling Android on Mac is not currently supported by gyp.
 # It doesn't appear to be supported on Windows either.
 # As of now, we will only support cross compiling on Linux.
 # libjpeg-turbo assembly code for x86 and x86-64 Android devices
 # must be disabled for Android on non-Linux platforms because
 # of this issue.  We still support compiling on Mac and other
 # variants for local development, but shipping versions of Skia
 # should be compiled on Linux for performance reasons.
 # TODO (msarett): Collect more information about this.
 if [ $(uname) == "Linux" ]; then
-  if [ -z $USE_CLANG ]; then
+  if [ "$USE_CLANG" != "true" ]; then
     exportVar CC_target "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-gcc"
     exportVar CXX_target "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-g++"
     exportVar LINK_target "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-gcc"
     exportVar CC_host "$CCACHE cc"
     exportVar CXX_host "$CCACHE c++"
     exportVar LINK_host "$CCACHE cc"
   else
-    # temporarily disable ccache as it is generating errors
-    CCACHE=""
     exportVar CC_target "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-clang"
     exportVar CXX_target "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-clang++"
     exportVar LINK_target "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-clang"
     exportVar CC_host "$CCACHE clang"
     exportVar CXX_host "$CCACHE clang++"
     exportVar LINK_host "$CCACHE clang"
   fi
 
   exportVar AR_target "$ANDROID_TOOLCHAIN_PREFIX-ar"
   exportVar RANLIB_target "$ANDROID_TOOLCHAIN_PREFIX-ranlib"
   exportVar OBJCOPY_target "$ANDROID_TOOLCHAIN_PREFIX-objcopy"
   exportVar STRIP_target "$ANDROID_TOOLCHAIN_PREFIX-strip"
   exportVar AR_host "ar"
   exportVar RANLIB_host "ranlib"
   exportVar OBJCOPY_host "objcopy"
   exportVar STRIP_host "strip"
 else
-  if [ -z $USE_CLANG ]; then
+  if [ "$USE_CLANG" != "true" ]; then
     exportVar CC "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-gcc"
     exportVar CXX "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-g++"
     exportVar LINK "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-gcc"
   else
-    # temporarily disable ccache as it is generating errors
-    CCACHE=""
     exportVar CC "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-clang"
     exportVar CXX "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-clang++"
     exportVar LINK "$CCACHE $ANDROID_TOOLCHAIN_PREFIX-clang"
   fi
 
   exportVar AR "$ANDROID_TOOLCHAIN_PREFIX-ar"
   exportVar RANLIB "$ANDROID_TOOLCHAIN_PREFIX-ranlib"
   exportVar OBJCOPY "$ANDROID_TOOLCHAIN_PREFIX-objcopy"
   exportVar STRIP "$ANDROID_TOOLCHAIN_PREFIX-strip"
 fi
 
 # Create symlinks for nm & readelf and add them to the path so that the ninja
 # build uses them instead of attempting to use the one on the system.
 # This is required to build using ninja on a Mac.
 if [ $(uname) == "Darwin" ]; then
   ln -sf $ANDROID_TOOLCHAIN_PREFIX-nm $ANDROID_TOOLCHAIN/nm
   ln -sf $ANDROID_TOOLCHAIN_PREFIX-readelf $ANDROID_TOOLCHAIN/readelf
   ln -sf $ANDROID_TOOLCHAIN_PREFIX-as $ANDROID_TOOLCHAIN/as
 fi
 
+# fix bug in the toolchain in order to enable ccache to work with clang
+if [ $(head -c 2 $ANDROID_TOOLCHAIN_PREFIX-clang) != "#!" ]; then
+   echo -e "#!/bin/bash\n$(cat $ANDROID_TOOLCHAIN_PREFIX-clang)" > $ANDROID_TOOLCHAIN_PREFIX-clang
+fi
+if [ $(head -c 2 $ANDROID_TOOLCHAIN_PREFIX-clang++) != "#!" ]; then
+   echo -e "#!/bin/bash\n$(cat $ANDROID_TOOLCHAIN_PREFIX-clang++)" > $ANDROID_TOOLCHAIN_PREFIX-clang++
+fi
+
 exportVar PATH $ANDROID_TOOLCHAIN:$PATH