libc: Add madvise stub

libc/include/sys/mman.h

@@ -14,6 +14,9 @@
 #define MS_ASYNC 2
 #define MS_INVALIDATE 4
 
+#define MADV_NORMAL 0
+#define MADV_RANDOM 1
+
 #ifdef __cplusplus
 extern "C"
 {
@@ -28,6 +31,9 @@ extern "C"
     /* Write modified shared memory back to its associated file. */
     int msync(void* addr, size_t len, int flags);
 
+    /* Give advice about the use of memory. */
+    int madvise(void* addr, size_t length, int advice);
+
     /* Create a new POSIX shared memory object. */
     int shm_open(const char* name, int oflag, mode_t mode);
 

libc/src/sys/mman.cpp

@@ -28,6 +28,12 @@ extern "C"
         __errno_return(rc, int);
     }
 
+    int madvise(void*, size_t, int)
+    {
+        // FIXME: Use this information to improve performance.
+        return 0;
+    }
+
     int shm_open(const char* name, int oflag, mode_t mode)
     {
         char buf[BUFSIZ];