[ion] Fix the C API

Change-Id: Ifbe11515171d7ee919f90fb28d63907c3c4cfd42

ion/Makefile

@@ -1,6 +1,10 @@
 SFLAGS += -Iion/include -DKD_CONFIG_H=1
 include ion/src/$(PLATFORM)/Makefile
 
+objs += $(addprefix ion/src/, \
+  c.o \
+)
+
 tests += $(addprefix ion/test/,\
   crc32.cpp\
 )

ion/include/ion/c.h

@@ -5,10 +5,10 @@
 extern "C" {
 #endif
 
-void ion_log_print(const char * message) {
+void ion_log_print(const char * message);
 
 #ifdef __cplusplus
-extern "C" {
+}
 #endif
 
 #endif

ion/src/simulator/Makefile

@@ -10,6 +10,7 @@ objs += $(addprefix ion/src/shared/, \
   crc32.o \
   events.o \
   events_from_keyboard.o \
+  log.o \
   power.o \
 )