Fix CPAN random tester regressions

[fglock]

Summary

• add bundled Digest::SHA1 compatibility for CPAN modules that still depend on Digest::SHA1
• fix warning state so normal use warnings downgrades inherited FATAL warning bits
• honor CORE::GLOBAL overrides for localtime and gmtime, which unblocks Test::MockTime
• make use vars qw(*name) predeclare scalar, array, and hash slots under strict vars
• add dependency-only CPAN distroprefs/patches for known PerlOnJava test-surface blockers

Test Plan

• timeout 1200 make > /tmp/make_cpan_regressions_8.log 2>&1
• timeout 600 ./jcpan -t HTTP::Cookies > /tmp/cpan_regress_HTTP-Cookies_after2.log 2>&1
• timeout 1200 ./jcpan -t URI::Fetch::SimpleCache > /tmp/cpan_regress_URI-Fetch-SimpleCache_after2.log 2>&1
• timeout 1200 ./jcpan -t MooX > /tmp/cpan_regress_MooX_after2.log 2>&1
• timeout 1200 ./jcpan -t CGI::Header > /tmp/cpan_regress_CGI-Header_after2.log 2>&1
• timeout 1200 ./jcpan -t Event::Notify > /tmp/cpan_regress_Event-Notify_after2.log 2>&1
• timeout 1200 ./jcpan -t Test::SubCalls > /tmp/cpan_regress_Test-SubCalls_after2.log 2>&1
• timeout 1200 ./jcpan -t IO::Scalar > /tmp/cpan_regress_IO-Scalar_after1.log 2>&1

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