Fix compilation on Windows

glextloader.c

@@ -31,6 +31,11 @@ static PFNGLCHECKFRAMEBUFFERSTATUSPROC glCheckFramebufferStatus = NULL;
 static PFNGLUNIFORM1IPROC glUniform1i = NULL;
 static PFNGLDRAWBUFFERSPROC glDrawBuffers = NULL;
 static PFNGLUNIFORM4FPROC glUniform4f = NULL;
+// TODO: there is something fishy with Windows gl.h header
+// Let's try to ship our own gl.h just like glext.h
+#ifdef _WIN32
+static PFNGLACTIVETEXTUREPROC glActiveTexture = NULL;
+#endif // _WIN32
 
 static void load_gl_extensions(void)
 {
@@ -67,6 +72,9 @@ static void load_gl_extensions(void)
     glUniform1i               = (PFNGLUNIFORM1IPROC) glfwGetProcAddress("glUniform1i");
     glDrawBuffers             = (PFNGLDRAWBUFFERSPROC) glfwGetProcAddress("glDrawBuffers");
     glUniform4f               = (PFNGLUNIFORM4FPROC) glfwGetProcAddress("glUniform4f");
+#ifdef _WIN32
+    glActiveTexture           = (PFNGLACTIVETEXTUREPROC) glfwGetProcAddress("glActiveTexture");
+#endif // _WIN32
 
     if (glfwExtensionSupported("GL_ARB_debug_output")) {
         fprintf(stderr, "INFO: ARB_debug_output is supported\n");