Regex library needs to push the SC it builds onto the compiling stack…

… while doing so, to prevent spurious repossession; clears up all but two instances in the build of the barrier triggering (which it never should in the NQP build).

src/Regex.pir

@@ -47,6 +47,7 @@ This file brings together the various Regex modules needed for Regex.pbc .
     # Create a serialization context for this compilation unit.
     .local pmc sc
     sc = nqp_create_sc "__REGEX_CORE_SC__"
+    nqp_push_compiling_sc sc
 
     # Load setting.
     load_bytecode 'ModuleLoader.pbc'
@@ -132,6 +133,9 @@ This file brings together the various Regex modules needed for Regex.pbc .
     hllns = get_hll_namespace
     imports = split ' ', 'PAST _dumper'
     parrotns.'export_to'(hllns, imports)
+
+    # Pop SC off current SCs stack.
+    nqp_pop_compiling_sc
 .end
 
 =head1 AUTHOR