Make tests and examples use glad

examples/particles.c

@@ -39,6 +39,7 @@
 #include <getopt.h>
 #include <linmath.h>
 
+#include <glad/glad.h>
 #include <GLFW/glfw3.h>
 
 // Define tokens for GL_EXT_separate_specular_color if not already defined
@@ -989,6 +990,7 @@ int main(int argc, char** argv)
         glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
 
     glfwMakeContextCurrent(window);
+    gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);
     glfwSwapInterval(1);
 
     glfwSetFramebufferSizeCallback(window, resize_callback);