eclass/toolchain.eclass: do not die if uclibc patches are not available

gcc-6 and above no longer needs uclibc specific patches, so we don't die if
the patchset is not available.  We do, however, still apply it if UCLIBC_VER
is defined in the ebuild to future proof the code in case we need to reintroduce
the patchset in the future.

eclass/toolchain.eclass

@@ -378,9 +378,6 @@ toolchain_pkg_pretend() {
  "in your make.conf if you want to use this version."
  fi
 
- [[ -z ${UCLIBC_VER} ]] && [[ ${CTARGET} == *-uclibc* ]] && \
- die "Sorry, this version does not support uClibc"
-
  if ! use_if_iuse cxx ; then
  use_if_iuse go && ewarn 'Go requires a C++ compiler, disabled due to USE="-cxx"'
  use_if_iuse objc++ && ewarn 'Obj-C++ requires a C++ compiler, disabled due to USE="-cxx"'