libc: Add support for the new clock() system call

libs/libc/include/luna/syscall.h

@@ -16,6 +16,7 @@
 #define SYS_exec 12
 #define SYS_fcntl 13
 #define SYS_mprotect 14
+#define SYS_clock 15
 
 #ifndef __want_syscalls
 #ifdef __cplusplus

libs/libc/include/time.h

@@ -0,0 +1,22 @@
+#ifndef _TIME_H
+#define _TIME_H
+
+typedef long int clock_t;
+typedef long int time_t;
+
+#define CLOCKS_PER_SEC 1000
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    /* Returns a number representing how much CPU time has been used by this process. Divide this by CLOCKS_PER_SEC to
+     * get the value in seconds. */
+    clock_t clock(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libs/libc/src/time.cpp

@@ -0,0 +1,11 @@
+#include <sys/syscall.h>
+#include <time.h>
+#include <unistd.h>
+
+extern "C"
+{
+    clock_t clock()
+    {
+        return syscall(SYS_clock);
+    }
+}

libs/libc/src/unistd.cpp

@@ -32,6 +32,7 @@ extern "C"
         va_start(ap, number);
         switch (number)
         {
+        case SYS_clock:
         case SYS_yield:
         case SYS_gettid: result = __luna_syscall0(number); break;
         case SYS_exit: