configure: update ax_code_coverage.m4 from autoconf-archive master
configure: update ax_code_coverage.m4 from autoconf-archive master

This enables support for lcov version 1.12.

Signed-off-by: Jan Luebbe <3a82f1ac4ad59607a20f180f1c67ac8ba31ad0d5@pengutronix.de>

rauc/rauc,ejoerns/rauc,jluebbe/rauc,ejoerns/rauc,jluebbe/rauc,ejoerns/rauc,rauc/rauc,rauc/rauc,jluebbe/rauc