[core] Create function to retrieve frame busy time (non-sleeping time)

src/raylib.h

@@ -1061,6 +1061,7 @@ RLAPI Matrix GetCameraMatrix2D(Camera2D camera);                        // Get c
 // Timing-related functions
 RLAPI void SetTargetFPS(int fps);                                 // Set target FPS (maximum)
 RLAPI float GetFrameTime(void);                                   // Get time in seconds for last frame drawn (delta time)
+RLAPI float GetFrameBusyTime(void);                               // Get the time spent actively updating and drawing a frame, excluding sleep time.
 RLAPI double GetTime(void);                                       // Get elapsed time in seconds since InitWindow()
 RLAPI int GetFPS(void);                                           // Get current FPS
 

src/rcore.c

@@ -1633,6 +1633,13 @@ float GetFrameTime(void)
     return (float)CORE.Time.frame;
 }
 
+
+// Get the time spent actively updating and drawing a frame, excluding sleep time.
+float GetFrameBusyTime(void)
+{
+    return (float)(CORE.Time.update + CORE.Time.draw);
+}
+
 //----------------------------------------------------------------------------------
 // Module Functions Definition: Custom frame control
 //----------------------------------------------------------------------------------