Solution: import ax_valgrind_check.m4 macro file to provide a
conveniente automake hook to run Valgrind on all tests.
Add --enable-valgrind to ./configure call and then run make
check-valgrind to run memcheck, helgrind, drd and sgcheck on all
tests. Run check-valgrind-memcheck to run only memcheck.

Solution: import ax_code_coverage.m4 from autoconf-archive and use it
in configure.ac and Makefile.am in order to provide a make
check-code-coverage target behind a --enable-code-coverage configure
flag, that can be used to generate a gcov/lcov code coverage report.
Depends on having gcov and lcov installed.

Solution: import macros to check for compiler options from
autoconf-archive into the m4 subdir.