Configure: Allow LC_ALL syntax override

Fixes #22992

The problem here had to do with cross-compilation.  There was no way to
override Perl's calculation of how LC_ALL is represented.  I had not put
one in because it is hard to get it right manually.  But this doesn't
work in cross-compilation; it's better to have a difficult-to-get-right
way than no way at all.

I don't know where to document this.  You need to specify in a hints
file:

    perl_lc_all_separator="correct-value"
    perl_lc_all_category_positions_init="correct-value"

Author: khwilliamson

Configure

@@ -17484,6 +17484,8 @@ $rm_try
     esac
 esac
 
+case "$perl_lc_all_separator$perl_lc_all_category_positions_init" in
+  "")
 : Check the syntax of LC_ALL when categories are set to different locales
 echo " "
 $echo "Checking the syntax of LC_ALL when categories are set to different locales..." >&4
@@ -17861,6 +17863,14 @@ $rm -f try try.*
           d_perl_lc_all_uses_name_value_pairs="$define"
 ;;
 esac
+;;
+
+  *)    # Has an lc_all definition passed-in
+     d_perl_lc_all_separator="$define"
+     d_perl_lc_all_category_positions_init="$define"
+     d_perl_lc_all_uses_name_value_pairs="$undef"
+     ;;
+esac
 
 : see if pipe2 exists
 set pipe2 d_pipe2