PERL_DEB() is missing from this old perl.
# if XSH_HAS_PERL(5, 8, 9) || XSH_HAS_PERL(5, 9, 3)
# define XSH_ASSERT(C) assert(C)
# else
-# define XSH_ASSERT(C) PERL_DEB( \
+# ifdef PERL_DEB
+# define XSH_DEB(X) PERL_DEB(X)
+# else
+# define XSH_DEB(X) (X)
+# endif
+# define XSH_ASSERT(C) XSH_DEB( \
((C) ? ((void) 0) \
: (Perl_croak_nocontext("Assertion %s failed: file \"" __FILE__ \
"\", line %d", STRINGIFY(C), __LINE__), \