libidn2: Fix charset.alias issue with musl

libidn2: Fix charset.alias issue with musl

Fixes
ERROR: libidn2-2.0.5-r0 do_package: QA Issue: libidn2: Files/directories were installed but not shipped in any packag
e:
  /usr/lib/charset.alias
Please set FILES such that these items are packaged. Alternatively if they are unneeded, avoid installing them or del
ete them within do_install.

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>