go.bbclass: fix path to linker in native Go builds

Building native Go tools results in the tool pointing to the wrong
location of dynamic linker (see below). The linker is looked up in the
temporary dir, which can be removed if rm_work is inherited. This
results in being unable to execute the program with the 'No such file or
directory' error. Override linker specificiation for native recipes (and
let Go build environment to pick up a correct one on it's own).

The error is observed in case the distro doesn't use uninative.bbclass.

If uninative.bbclass is used, the binary will be patched automatically
to use the uninative loader instead of the system one.

Without this patch:

$ ldd tmp-rpb-glibc/sysroots-components/x86_64/go-md2man-native/usr/bin/go-md2man
	linux-vdso.so.1 (0x00007ffe945ec000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3a7490e000)
	/home/lumag/Projects/RPB/build-rpb/tmp-rpb-glibc/work/x86_64-linux/go-md2man-native/1.0.10+gitAUTOINC+f79a8a8ca6-r0/recipe-sysroot-native/usr/lib/ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2 (0x00007f3a74d13000)
$ tmp-rpb-glibc/sysroots-components/x86_64/go-md2man-native/usr/bin/go-md2man  --help
-bash: tmp-rpb-glibc/sysroots-components/x86_64/go-md2man-native/usr/bin/go-md2man: No such file or directory

With the patch

$ ldd tmp-rpb-glibc/sysroots-components/x86_64/go-md2man-native/usr/bin/go-md2man
	linux-vdso.so.1 (0x00007ffd19dbf000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f2d44181000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f2d44586000)
$ tmp-rpb-glibc/sysroots-components/x86_64/go-md2man-native/usr/bin/go-md2man  --help
Usage of tmp-rpb-glibc/sysroots-components/x86_64/go-md2man-native/usr/bin/go-md2man:
  -in string
	Path to file to be processed (default: stdin)
  -out string
	Path to output processed file (default: stdout)

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>