Integrate changes #8704,8710 from pureperl.

Integrate changes #8704,8710 from pureperl.

Fixed UMRs and leak in Perl_pmtrans()

Several leaks an UMRs fixed, mainly in the area of Perl_pmtrans and
associated UTFied tr/// code.  Also fixed scoping leak of
PL_reg_start_tmp.

p4raw-link: @8710 on //depot/maint-5.6/pureperl: 4b295d51b64a7a209f5040a76fc8fbb310bcc094
p4raw-link: @8704 on //depot/maint-5.6/pureperl: a0f842d35079c52aadb60790fe59b37d9727c9a9

p4raw-id: //depot/perl@8735
p4raw-integrated: from //depot/maint-5.6/pureperl@8734 'edit in' op.c
	(@8704..) 'merge in' regcomp.c (@8694..)