Add SERVAL_ENABLE_DEBUG macro

Android.mk

@@ -28,6 +28,7 @@ SERVALD_LOCAL_CFLAGS = \
 	-Wno-unknown-attributes \
         -DSERVALD_VERSION="\"Android\"" -DSERVALD_COPYRIGHT="\"Android\"" \
 	-DINSTANCE_PATH="\"/data/data/org.servalproject/var/serval-node\"" \
+	-DSERVAL_ENABLE_DEBUG=1 \
         -DSHELL -DPACKAGE_NAME=\"\" -DPACKAGE_TARNAME=\"\" -DPACKAGE_VERSION=\"\" \
         -DPACKAGE_STRING=\"\" -DPACKAGE_BUGREPORT=\"\" -DPACKAGE_URL=\"\" \
 	-DHAVE_FUNC_ATTRIBUTE_ERROR=1 \

Makefile.in

@@ -79,6 +79,7 @@ CFLAGS+=-DSQLITE_THREADSAFE=0 \
 	-DSQLITE_OMIT_AUTHORIZATION
 CFLAGS+=-fPIC
 CFLAGS+=-Wall -Werror
+CFLAGS+=-DSERVAL_ENABLE_DEBUG=1
 # Solaris magic
 CFLAGS+=-DSHA2_USE_INTTYPES_H -D_XOPEN_SOURCE=600 -D_XOPEN_SOURCE_EXTENDED=1 -D__EXTENSIONS__=1
 # OSX magic to compensate for the Solaris magic

conf.h

@@ -704,7 +704,15 @@ extern __thread int cf_initialised;
 extern __thread int cf_limbo;
 extern __thread struct config_main config;
 
+// This macro is used in an if (IF_DEBUG(flagname)) { } statement around all
+// debugging log statements.  If macro SERVAL_ENABLE_DEBUG can be pre-defined as 0
+// (eg, using the -D command-line option) to build without any debug
+// statements.
+#if SERVAL_ENABLE_DEBUG+0
 #define IF_DEBUG(flagname) (config.debug.flagname)
+#else
+#define IF_DEBUG(flagname) (0)
+#endif
 
 int cf_init(void);
 int cf_load(void);