Linking fails if source path contains spaces

To reproduce:

    $ mkdir -p "/tmp/path with space/build"
    $ cp -a zlib /tmp/path\ with\ space/
    $ cd /tmp/path\ with\ space/build
    $ cmake ../zlib
    ...
     -- Build files have been written to: /tmp/path with space/build
    $ make 
    Scanning dependencies of target zlib
    [  3%] Building C object CMakeFiles/zlib.dir/adler32.o
    [  6%] Building C object CMakeFiles/zlib.dir/compress.o
    [  9%] Building C object CMakeFiles/zlib.dir/crc32.o
    [ 12%] Building C object CMakeFiles/zlib.dir/deflate.o
    [ 15%] Building C object CMakeFiles/zlib.dir/gzclose.o
    [ 18%] Building C object CMakeFiles/zlib.dir/gzlib.o
    [ 21%] Building C object CMakeFiles/zlib.dir/gzread.o
    [ 25%] Building C object CMakeFiles/zlib.dir/gzwrite.o
    [ 28%] Building C object CMakeFiles/zlib.dir/inflate.o
    [ 31%] Building C object CMakeFiles/zlib.dir/infback.o
    [ 34%] Building C object CMakeFiles/zlib.dir/inftrees.o
    [ 37%] Building C object CMakeFiles/zlib.dir/inffast.o
    [ 40%] Building C object CMakeFiles/zlib.dir/trees.o
    [ 43%] Building C object CMakeFiles/zlib.dir/uncompr.o
    [ 46%] Building C object CMakeFiles/zlib.dir/zutil.o
        Linking C shared library libz.dylib
    i686-apple-darwin11-llvm-gcc-4.2: with: No such file or directory
    i686-apple-darwin11-llvm-gcc-4.2: space/zlib/zlib.map: No such file or directory
    make[2]: *** [libz.1.2.7.dylib] Error 1
    make[1]: *** [CMakeFiles/zlib.dir/all] Error 2
    make: *** [all] Error 2

This commit explicitly quotes the path in `-Wl,--version-script,<path>`.