various fixes (#49)

* libs: libc: math: Fix tanh() math functions
* drivers: mtd: smart: Fix trivial debug message in smartfs
* binfmt: libelf: Fix fd not closed on error
* binfmt: Fix stack memory leak on error
* fs: romfs: Fix private data not free on error
* sched: group: Fix reference after free memory
* sched: clock: Fix clock sync

Fix clock sync when CONFIG_RTC_HIRES is enabled

fs/romfs/fs_romfs.c

@@ -268,6 +268,7 @@ static int romfs_open(FAR struct file *filep, FAR const char *relpath,
   if (ret < 0)
     {
       ferr("ERROR: Failed to locate start of file data: %d\n", ret);
+      kmm_free(rf);
       goto errout_with_semaphore;
     }
 
@@ -277,6 +278,7 @@ static int romfs_open(FAR struct file *filep, FAR const char *relpath,
   if (ret < 0)
     {
       ferr("ERROR: Failed configure buffering: %d\n", ret);
+      kmm_free(rf);
       goto errout_with_semaphore;
     }