Fix intinite loop of cmake wrapper of osxcross.

[iwasakims]

Running cmake in the container with CROSS_TRIPLE=x86_64-apple-darwin hangs. The cause is wrapper of cmake (osxcross-cmake). Running cmake in the script results in recursively calling itself due to the PATH in the container.

root@6955a97b22e3:/workdir# /usr/bin/cmake --version
cmake version 3.7.2

CMake suite maintained and supported by Kitware (kitware.com/cmake).

root@6955a97b22e3:/workdir# which cmake
/usr/x86_64-apple-darwin14/bin/cmake

root@6955a97b22e3:/workdir# cat /usr/x86_64-apple-darwin14/bin/cmake
#!/bin/bash

# set -x

# check if we are a symlink
if [ "$(readlink -f $0)" != "$0" ]; then
    exec "$(readlink -f $0)" $@
    exit $?
fi

# normal behavior -> proxy to osxcross binary
triple=$(echo "$0" | cut -d/ -f3)
binary=$(basename "$0")
binary_path="/usr/osxcross/bin/$triple-$binary"

exec "$binary_path" $@

# ls -l /usr/osxcross/bin/x86_64-apple-darwin14-cmake
lrwxrwxrwx. 1 root root 14 Oct 20 12:29 /usr/osxcross/bin/x86_64-apple-darwin14-cmake -> osxcross-cmake

root@6955a97b22e3:/workdir# cat /usr/osxcross/bin/osxcross-cmake
#!/usr/bin/env bash
set -e

dir=`dirname "$0"`
progname=`basename "$0"`

host=${progname%-cmake}
if test "$host" = "osxcross" ; then
   echo "Do not invoke this script directly."
   exit 1
fi

eval "`$dir/$host-osxcross-conf`"
export OSXCROSS_HOST="$host"

exec cmake -DCMAKE_TOOLCHAIN_FILE="$OSXCROSS_TARGET_DIR"/toolchain.cmake "$@"