basic: turn off stdio locking for a couple of helper calls

These helper calls are potentially called often, and allocate FILE*
objects internally for a very short period of time, let's turn off
locking for them too.

src/basic/cgroup-util.c

@@ -24,6 +24,7 @@
 #include <limits.h>
 #include <signal.h>
 #include <stddef.h>
+#include <stdio_ext.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -1032,6 +1033,8 @@ int cg_pid_get_path(const char *controller, pid_t pid, char **path) {
         if (!f)
                 return errno == ENOENT ? -ESRCH : -errno;
 
+        (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
+
         FOREACH_LINE(line, f, return -errno) {
                 char *e, *p;
 
@@ -2371,6 +2374,8 @@ int cg_kernel_controllers(Set **ret) {
                 return -errno;
         }
 
+        (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
+
         /* Ignore the header line */
         (void) read_line(f, (size_t) -1, NULL);