[client] imgui: added imgui to the client and OpenGL/EGL renderers

client/include/app.h

@@ -78,6 +78,8 @@ void app_glSetSwapInterval(int interval);
 void app_glSwapBuffers(void);
 #endif
 
+bool app_renderImGui(void);
+
 void app_clipboardRelease(void);
 void app_clipboardNotifyTypes(const LG_ClipboardData types[], int count);
 void app_clipboardNotifySize(const LG_ClipboardData type, size_t size);

client/include/egl_dynprocs.h

@@ -25,6 +25,9 @@
 #include <EGL/egl.h>
 #include <GL/gl.h>
 
+// if GLEW is included, GLeglImageOES was not defined
+typedef void * GLeglImageOES;
+
 typedef EGLDisplay (*eglGetPlatformDisplayEXT_t)(EGLenum platform,
     void *native_display, const EGLint *attrib_list);
 typedef void (*eglSwapBuffersWithDamageKHR_t)(EGLDisplay dpy,