crossdev stores the EXTRA_ECONF options w/o quotes

Hi,

Minor bug in crossdev, as the title says its storing the options I
passed without the quotes.  That means emerge spills some messages about
'command not found' referring to the second options on those lines.

Here's an example of what I'm doing (mind you it doesn't work for what
its intended -- i.e. the mingw-w64 tools are not quite right, they are
missing the 32 bit libc++ and other details):

$ sudo crossdev -t x86_64-w64-mingw32 \
> --b 2.22 --g 4.6.2 \
> --benv
EXTRA_ECONF="--enable-targets=x86_64-w64-mingw32,i686-w64-mingw32" \
> --genv EXTRA_ECONF="--enable-multilib --enable-targets=all" \
> --lenv EXTRA_ECONF="--enable-lib64 --enable-lib32"

That command succeeds.

Later using emerge for my weekly update:

/etc/portage/env/cross-x86_64-w64-mingw32/mingw64-runtime: line 2:
--enable-lib32: command not found
/etc/portage/env/cross-x86_64-w64-mingw32/gcc: line 2:
--enable-targets=all: command not found

And the offending lines:

$ head -n 2 /etc/portage/env/cross-x86_64-w64-mingw32/mingw64-runtime
/etc/portage/env/cross-x86_64-w64-mingw32/gcc