shared/logging: add "nm-logging-base.h"

We have "nm-logging-fwd.h", which (as the name implies) is header-only.
Add instead a "nm-logging-base.c", which also contains implementation for
logging functions that are not only useful under "src/nm-logging.c"

Makefile.am

@@ -402,6 +402,8 @@ shared_nm_glib_aux_libnm_glib_aux_la_SOURCES = \
 	shared/nm-glib-aux/nm-json-aux.h \
 	shared/nm-glib-aux/nm-keyfile-aux.c \
 	shared/nm-glib-aux/nm-keyfile-aux.h \
+	shared/nm-glib-aux/nm-logging-base.c \
+	shared/nm-glib-aux/nm-logging-base.h \
 	shared/nm-glib-aux/nm-logging-fwd.h \
 	shared/nm-glib-aux/nm-macros-internal.h \
 	shared/nm-glib-aux/nm-obj.h \

shared/meson.build

@@ -137,6 +137,7 @@ sources = files(
   'nm-glib-aux/nm-io-utils.c',
   'nm-glib-aux/nm-json-aux.c',
   'nm-glib-aux/nm-keyfile-aux.c',
+  'nm-glib-aux/nm-logging-base.c',
   'nm-glib-aux/nm-random-utils.c',
   'nm-glib-aux/nm-ref-string.c',
   'nm-glib-aux/nm-secret-utils.c',

shared/nm-glib-aux/nm-logging-base.c

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: LGPL-2.1+
+
+#include "nm-default.h"
+
+#include "nm-logging-base.h"

shared/nm-glib-aux/nm-logging-base.h

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: LGPL-2.1+
+
+#ifndef __NM_LOGGING_BASE_H__
+#define __NM_LOGGING_BASE_H__
+
+#include "nm-logging-fwd.h"
+
+#endif /* __NM_LOGGING_BASE_H__ */