frecon: Define get_monotonic_time_ms as static inline.

get_monotonic_time_ms is declared as inline and therefore
is not included in any object files.
This breaks linking in coverage builds.

Fixes following linker error with USE=coverage.
dbus.pie.o:dbus.c:__profd_get_monotonic_time_ms:
 error: undefined reference to 'get_monotonic_time_ms'

BUG=chromium:961510
TEST=USE=coverage emerge-amd64-generic frecon works.

Change-Id: Ib2c5d223d448d39f5a86f29862221e86056bf38b
Reviewed-on: https://chromium-review.googlesource.com/1604309
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Dominik Behr <dbehr@chromium.org>
diff --git a/util.h b/util.h
index 776fc5a..e1ba8eb 100644
--- a/util.h
+++ b/util.h
@@ -26,7 +26,7 @@
 #define  NS_PER_MS              (NS_PER_SEC / MS_PER_SEC);
 
 /* Returns the current CLOCK_MONOTONIC time in milliseconds. */
-inline int64_t get_monotonic_time_ms() {
+static inline int64_t get_monotonic_time_ms() {
 	struct timespec spec;
 	clock_gettime(CLOCK_MONOTONIC, &spec);
 	return MS_PER_SEC * spec.tv_sec + spec.tv_nsec / NS_PER_MS;