LibC: Implement wait()

This is a simple convenience wrapper over waitpid().

Libraries/LibC/unistd.cpp

@@ -236,6 +236,11 @@ pid_t waitpid(pid_t waitee, int* wstatus, int options)
     __RETURN_WITH_ERRNO(rc, rc, -1);
 }
 
+pid_t wait(int* wstatus)
+{
+    return waitpid(-1, wstatus, 0);
+}
+
 int lstat(const char* path, struct stat* statbuf)
 {
     int rc = syscall(SC_lstat, path, statbuf);

Libraries/LibC/unistd.h

@@ -66,6 +66,7 @@ ssize_t read(int fd, void* buf, size_t count);
 ssize_t write(int fd, const void* buf, size_t count);
 int close(int fd);
 pid_t waitpid(pid_t, int* wstatus, int options);
+pid_t wait(int* wstatus);
 int chdir(const char* path);
 char* getcwd(char* buffer, size_t size);
 char* getwd(char* buffer);