Before 9197c1ac, the AC_ARG_ENABLE(log_macros, ...) action was hardcoded to [log_macros="yes"], so *any* use of the flag --enable-log-macros or --disable-log-macros would set log_macros="yes" -> AC_DEFINE([LIBOSMOCORE_NO_LOGGING]).
The commit changed this to the standard [log_macros=$enableval], but broke the conditional test, so - AC_ARG_ENABLE sets $enableval to "no" for --disable-* flags -> log_macros is now "no" -> test fails -> LIBOSMOCORE_NO_LOGGING is never defined...
