Configuration through environment variable is inconvenient with meson, because
they cannot be convieniently changed and/or are not preserved during
reconfiguration (https://github.com/mesonbuild/meson/issues/1503).
This adds -Dvalgrind=true/false, which has the advantage that it can be set
at any time with meson configure -Dvalgrind=... and ninja will rebuild targets
as necessary. Additional minor advantages are better consistency with the
options for hashmap debugging, and typo avoidance with '#if' instead of '#ifdef'.
Double newlines (i.e. one empty lines) are great to structure code. But
let's avoid triple newlines (i.e. two empty lines), quadruple newlines,
quintuple newlines, …, that's just spurious whitespace.
It's an easy way to drop 121 lines of code, and keeps the coding style
of our sources a bit tigther.
Fixed (master) versions of libtool pass -fsanitize=address correctly
into CFLAGS and LDFLAGS allowing ASAN to be used without any special
configure tricks..however ASAN triggers in lookup3.c for the same
reasons valgrind does. take the alternative codepath if
__SANITIZE_ADDRESS__ is defined as well.
Ben Boeckel