Don't create an ortho matrix when the viewport is 0 in any axis. (#1504)

* Don't create an ortho matrix when the viewport is 0 in any axis.
Not all compilers divide by 0 and return inf, some segfault.
The matrix is not used by anything when minimized, so it just needs to not be called.

* Better fix that always ensures the rlgl matrix is always valid

* Better fix that always ensures the rlgl matrix is always valid

src/rlgl.h

@@ -1100,6 +1100,12 @@ void rlFrustum(double left, double right, double bottom, double top, double znea
 // Multiply the current matrix by an orthographic matrix generated by parameters
 void rlOrtho(double left, double right, double bottom, double top, double znear, double zfar)
 {
+    if (right - left <= 0 || bottom - top <= 0)
+    {
+        *RLGL.State.currentMatrix = MatrixIdentity();
+        return;
+    }
+
     Matrix matOrtho = MatrixOrtho(left, right, bottom, top, znear, zfar);
 
     *RLGL.State.currentMatrix = MatrixMultiply(*RLGL.State.currentMatrix, matOrtho);