systemcmds: convert c -> c++

src/systemcmds/perf/CMakeLists.txt

@@ -35,7 +35,7 @@ px4_add_module(
 	MAIN perf
 	COMPILE_FLAGS
 	SRCS
-		perf.c
+		perf.cpp
 	DEPENDS
 		perf
 	)

src/systemcmds/perf/perf.cpp

@@ -39,12 +39,9 @@
 #include <stdio.h>
 #include <string.h>
 
-#include <perf/perf_counter.h>
+#include <lib/perf/perf_counter.h>
 
-__EXPORT int perf_main(int argc, char *argv[]);
-
-
-static void print_usage(void)
+static void print_usage()
 {
 	PRINT_MODULE_DESCRIPTION("Tool to print performance counters");
 
@@ -55,8 +52,7 @@ static void print_usage(void)
 	PRINT_MODULE_USAGE_PARAM_COMMENT("Prints all performance counters if no arguments given");
 }
 
-
-int perf_main(int argc, char *argv[])
+extern "C" __EXPORT int perf_main(int argc, char *argv[])
 {
 	if (argc > 1) {
 		if (strcmp(argv[1], "reset") == 0) {
@@ -77,5 +73,3 @@ int perf_main(int argc, char *argv[])
 	fflush(stdout);
 	return 0;
 }
-
-