kconfig: prepend CT-NG's version tag to PKGVERSION

"crosstool-NG-${CT_VERSION}" is currently the default for TOOLCHAIN_PKGVERSION,
and this options is passed as is to --with-pkgversion.

This patch prepends "crosstool-NG ${CT_VERSION}" to TOOLCHAIN_PKGVERSION before
passing it to --with-pkgversion.

Signed-off-by: "Benoît THÉBAUDEAU" <benoit.thebaudeau@advansee.com>

 reporter_name="unknown"

 reporter_url="http://iphonelinux.org/index.php/Glibc_toolchain_using_crosstool-NG"

 reporter_comment="An (experimental) toolchain targeting the Apple's iPhone."