Remove PL_maxo

We have an interpreter variable using memory, PL_maxo, which is
defined to be the same as MAXO, a #defined constant.  As far as I can
tell, it is never used in lvalue context, in core or on CPAN, except
for the initialisation in intrpvar.h.

It can simply be removed and replaced with a macro defined as equiva-
lent to MAXO.

It was added in this commit:

commit 84ea024ac9cdf20f21223e686dddea82d5eceb4f
Author: Perl 5 Porters <perl5-porters.nicoh.com>
Date:   Tue Jan 2 23:21:55 1996 +0000

    perl 5.002beta1h patch: perl.h

    5.002beta1 attempted some memory optimizations, but unfortunately
    they can result in a memory leak problem.  This can be
    avoided by #define STRANGE_MALLOC.  I do that here until
    consensus is reached on a better strategy for handling the
    memory optimizations.

    Include maxo for the maximum number of operations (needed
    for the Safe extension).

But apparently it is not needed for the Safe extension (tests pass
without it).

1 files changed, 1 insertions, 0 deletions

diff --git a/perl.h b/perl.h
index 8a2e1f1587..43f1a532ea 100644
--- a/perl.h
+++ b/perl.h
@@ -5288,6 +5288,7 @@ EXTCONST char *const PL_phase_names[];
 #endif /* !PERL_CORE */
 
 #define PL_hints PL_compiling.cop_hints
+#define PL_maxo  MAXO
 
 END_EXTERN_C