Filter out problematic vars from the ct-ng sample

cross-compilers/compilers_generic/build.sh

@@ -53,7 +53,7 @@ if [[ ! -n $(find ${SRC_DIR}/gcc_built -iname ${cpu_arch}-${vendor}-*-gfortran)
     source ${RECIPE_DIR}/write_ctng_config
 
     yes "" | ct-ng ${ctng_sample}
-    write_ctng_config_before "${PWD}"/.config
+    write_ctng_config_before .config
     # Apply some adjustments for conda.
     sed -i.bak "s|# CT_DISABLE_MULTILIB_LIB_OSDIRNAMES is not set|CT_DISABLE_MULTILIB_LIB_OSDIRNAMES=y|g" .config
     sed -i.bak "s|CT_CC_GCC_USE_LTO=n|CT_CC_GCC_USE_LTO=y|g" .config
@@ -71,8 +71,12 @@ if [[ ! -n $(find ${SRC_DIR}/gcc_built -iname ${cpu_arch}-${vendor}-*-gfortran)
     fi
     # Now ensure any changes we made above pull in other requirements by running oldconfig.
     yes "" | ct-ng oldconfig
+    # Now filter out 'things that cause problems'. For example, depending on the base sample, you can end up with
+    # two different glibc versions in-play.
+    sed -i.bak '/CT_LIBC/d' .config
+    sed -i.bak '/CT_LIBC_GLIBC/d' .config
     # And undo any damage to version numbers => the seds above could be moved into this too probably.
-    write_ctng_config_after "${PWD}"/.config
+    write_ctng_config_after .config
     if cat .config | grep "CT_GDB_NATIVE=y"; then
       if ! cat .config | grep "CT_EXPAT_TARGET=y"; then
         echo "ERROR: CT_GDB_NATIVE=y but CT_EXPAT_TARGET!=y"

cross-compilers/compilers_generic/write_ctng_config

@@ -108,6 +108,10 @@ function write_ctng_package_versions() {
     "${_extras[@]}"; do
       write_config_var "${_dst}" "${_VAR_CT_VAR}"
   done
+  # Add this back here because build.sh filters out LIBC_GLIBC to prevent conflicts.
+  if [[ ${libc} == gnu ]]; then
+    echo "CT_LIBC_GLIBC_FORCE_UNWIND=y" >> "${_dst}"
+  fi
 }
 
 function write_ctng_config_before() {