Turn VALGRIND variable into a meson configuration switch

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'.

1 files changed, 6 insertions, 7 deletions

diff --git a/README b/README
index d18eb7dc1e..2cde08c37e 100644
--- a/README
+++ b/README
@@ -303,13 +303,12 @@ WARNINGS:
         For more information on this issue consult
         https://www.freedesktop.org/wiki/Software/systemd/separate-usr-is-broken
 
-        To run systemd under valgrind, compile with VALGRIND defined
-        (e.g. CPPFLAGS='... -DVALGRIND=1' meson <options>) and have valgrind
-        development headers installed (i.e. valgrind-devel or
-        equivalent). Otherwise, false positives will be triggered by code which
-        violates some rules but is actually safe. Note that valgrind generates
-        nice output only on exit(), hence on shutdown we don't execve()
-        systemd-shutdown.
+        To run systemd under valgrind, compile with meson option
+        -Dvalgrind=true and have valgrind development headers installed
+        (i.e. valgrind-devel or equivalent). Otherwise, false positives will be
+        triggered by code which violates some rules but is actually safe. Note
+        that valgrind generates nice output only on exit(), hence on shutdown
+        we don't execve() systemd-shutdown.
 
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