Fix rlsw persistent alpha blending state

Author: iztanos

src/external/rlsw.h

@@ -3947,6 +3947,7 @@ static void sw_immediate_push_vertex(const float position[4])
     // Copy the attributes in the current vertex
     for (int i = 0; i < 4; i++) vertex->color[i] = RLSW.primitive.color[i];
     for (int i = 0; i < 2; i++) vertex->texcoord[i] = RLSW.primitive.texcoord[i];
+    RLSW.primitive.hasColorAlpha |= (vertex->color[3] < 1.0f);
 
     // Immediate rendering of the primitive if the required number is reached
     if (RLSW.primitive.vertexCount == SW_PRIMITIVE_VERTEX_COUNT[RLSW.drawMode])