integrate cfgperl contents into mainline

p4raw-id: //depot/perl@4076

diff --cc perl.h
index e3d3826,dae4390..8973317
--- 1/perl.h
--- 2/perl.h
+++ b/perl.h
@@@ -1685,6 -1702,6 +1702,22 @@@ typedef pthread_key_t  perl_key
  #  endif
  #endif
  
++#if defined(PERL_IMPLICIT_CONTEXT) && !defined(PERL_GET_THX)
++#  ifdef USE_THREADS
++#    define PERL_GET_THX              THR
++#  else
++#  ifdef MULTIPLICITY
++#    define PERL_GET_THX              PERL_GET_INTERP
++#  else
++#  ifdef PERL_OBJECT
++#    define PERL_GET_THX              ((CPerlObj*)PERL_GET_INTERP)
++#  else
++#    define PERL_GET_THX              ((void*)0)
++#  endif
++#  endif
++#  endif
++#endif
++
  /* Some unistd.h's give a prototype for pause() even though
     HAS_PAUSE ends up undefined.  This causes the #define
     below to be rejected by the compmiler.  Sigh.

diff --cc perlapi.c
index f409754,1945146..1945146
mode 100644,100755..100644
--- 1/perlapi.c
--- 2/perlapi.c
+++ b/perlapi.c