Kernel/LibC: Implement very basic msync

libc/include/sys/syscall.h

@@ -61,6 +61,7 @@ __BEGIN_DECLS
 #define SYS_UNLINK 58
 #define SYS_READLINK 59
 #define SYS_READLINKAT 60
+#define SYS_MSYNC 61
 
 __END_DECLS
 

libc/sys/mman.cpp

@@ -22,3 +22,8 @@ int munmap(void* addr, size_t len)
 {
 	return syscall(SYS_MUNMAP, addr, len);
 }
+
+int msync(void* addr, size_t len, int flags)
+{
+	return syscall(SYS_MSYNC, addr, len, flags);
+}