Merge branch 'maint' * maint: tests: remove most uses of the AM_PROG_CC_C_O obsolete macro coverage: obsolete macro AM_PROG_CC_C_O should cause no warning nor errors INSTALL: update copyright years ithreads: use runtime (not configure time) detection of perl threads copyright: add few missing copyright notices maint: files in PLANS are to be exempted from copyright notice maint: consistently honor the UPDATE_COPYRIGHT_YEAR environment variable copyright: update some copyright years Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>