Upstream commit to support glxCopySubBufferMESA.  Modified to fix compile error with egl.

commit 4dc3f3bdc3611ca1b3dec402f9242a036db8c8e4
Author: Carl Worth <cworth@cworth.org>
Date:   Thu Oct 17 14:52:21 2013 -0700

    retrace: Implement glxCopySubBufferMESA
    
    This enables replay of a trace captured on ChromeOS.
    
    Note: Replaying on EGL is not supported, (will trigger a warning),
    since, as far as I know, EGL does not provide an equivalent function.

--- apitrace/retrace/glretrace_glx.cpp
+++ apitrace/retrace/glretrace_glx.cpp
@@ -111,6 +111,16 @@ static void retrace_glXDestroyContext(trace::Call &call) {
     delete context;
 }
 
+static void retrace_glXCopySubBufferMESA(trace::Call &call) {
+    glws::Drawable *drawable = getDrawable(call.arg(1).toUInt());
+    int x = call.arg(2).toSInt();
+    int y = call.arg(3).toSInt();
+    int width = call.arg(4).toSInt();
+    int height = call.arg(5).toSInt();
+
+    drawable->copySubBuffer(x, y, width, height);
+}
+
 static void retrace_glXSwapBuffers(trace::Call &call) {
     glws::Drawable *drawable = getDrawable(call.arg(1).toUInt());
 
@@ -173,7 +183,7 @@ const retrace::Entry glretrace::glx_callbacks[] = {
     {"glXChooseVisual", &retrace::ignore},
     //{"glXCopyContext", &retrace_glXCopyContext},
     //{"glXCopyImageSubDataNV", &retrace_glXCopyImageSubDataNV},
-    //{"glXCopySubBufferMESA", &retrace_glXCopySubBufferMESA},
+    {"glXCopySubBufferMESA", &retrace_glXCopySubBufferMESA},
     {"glXCreateContextAttribsARB", &retrace_glXCreateContextAttribsARB},
     {"glXCreateContext", &retrace_glXCreateContext},
     //{"glXCreateContextWithConfigSGIX", &retrace_glXCreateContextWithConfigSGIX},
--- apitrace/retrace/glws.hpp
+++ apitrace/retrace/glws.hpp
@@ -127,6 +127,8 @@ public:
         visible = true;
     }
 
+    virtual void copySubBuffer(int x, int y, int width, int height) = 0;
+
     virtual void swapBuffers(void) = 0;
 };
 
--- apitrace/retrace/glws_egl_xlib.cpp
+++ apitrace/retrace/glws_egl_xlib.cpp
@@ -244,6 +244,10 @@ public:
         Drawable::show();
     }
 
+    void copySubBuffer(int x, int y, int width, int height) {
+        std::cerr << "glws_egl_xlib: Warning: copySubBuffer Not yet implemented\n";
+    }
+
     void swapBuffers(void) {
         eglBindAPI(api);
         eglSwapBuffers(eglDisplay, surface);
--- apitrace/retrace/glws_glx.cpp
+++ apitrace/retrace/glws_glx.cpp
@@ -213,6 +213,12 @@ public:
         Drawable::show();
     }
 
+    void copySubBuffer(int x, int y, int width, int height) {
+        glXCopySubBufferMESA(display, window, x, y, width, height);
+
+        processKeys();
+    }
+
     void swapBuffers(void) {
         glXSwapBuffers(display, window);