Fix mistake in comments in seccomp sandbox

In src/common/sandbox.c, the comments for the sb_prctl() and sb_mprotect() functions both say they are for the fcntl64() syscall filter, probably because they were all copy pasted from that as a template.

--- src/common/sandbox.c
+++ src/common/sandbox.c
@@ -757,7 +757,7 @@
 }
 
 /**
- * Function responsible for setting up the fcntl64 syscall for
+ * Function responsible for setting up the prctl syscall for
  * the seccomp filter sandbox.
  *
  * NOTE: if multiple filters need to be added, the PR_SECCOMP parameter needs
@@ -778,7 +778,7 @@
 }
 
 /**
- * Function responsible for setting up the fcntl64 syscall for
+ * Function responsible for setting up the mprotect syscall for
  * the seccomp filter sandbox.
  *
  * NOTE: does not NEED to be here.. currently only occurs before filter; will