Fix for Coverity perl5 CID 29032: Out-of-bounds read (OVERRUN) overrun-local: Overrunning array anyofs of 34 8-byte elements at element index 34 (byte offset 272) using index index (which evaluates to 34).

Off-by-one error: because the test "index > number of elements"
should have used ">=", the anyofs[] could have been accessed one
past the end.  Use the C_ARRAY_LENGTH since we have it.
I think regprop is only used by -Mre=debug.
Fix for Coverity perl5 CID 29060: Pointer to local outside scope (RETURN_LOCAL) use_invalid: Using mode, which points to an out-of-scope variable tmode.

Duplicate the PerlIOBase_pushed call so that the tmode is in scope.
Fix for Coverity perl5 CID 29034: Out-of-bounds read (OVERRUN) overrun-local: Overrunning array PL_reg_intflags name of 14 8-byte elements at element index 31 (byte offset 248) using index bit (which evaluates to 31).

Needed compile-time limits for the PL_reg_intflags_name so that the
bit loop doesn't waltz off past the array.  Could not use C_ARRAY_LENGTH
because the size of name array is not visible during compile time
(only const char*[] is), so modified regcomp.pl to generate the size,
made it visible only under DEBUGGING.  Did extflags analogously
even though its size currently exactly 32 already.  The sizeof(flags)*8
is extra paranoia for ILP64.