Add an option for stable SC handles.

We can't do these in general thanks to the bootstrap, but we need it in
order to handle cross-compiling.

Author: jnthn

src/NQP/Compiler.pm

@@ -18,6 +18,7 @@ my @clo := $nqpcomp.commandline_options();
 @clo.push('no-regex-lib');
 @clo.push('old-regex-lib');
 @clo.push('dynext=s');
+@clo.push('stable-sc');
 
 sub MAIN(@ARGS) {
     # Enter the compiler.

src/NQP/Grammar.pm

@@ -19,7 +19,7 @@ grammar NQP::Grammar is HLL::Grammar {
         # with this compilation unit.
         my $file := pir::find_caller_lex__Ps('$?FILES');
         my $source_id := nqp::sha1(self.target()) ~
-            '-' ~ ~nqp::time_n();
+            (%*COMPILING<%?OPTIONS><stable-sc> ?? '' !! '-' ~ ~nqp::time_n());
         my $*W := nqp::isnull($file) ??
             NQP::World.new(:handle($source_id)) !!
             NQP::World.new(:handle($source_id), :description($file));