Fix envmap for double precision modes

Author: Speierers

src/emitters/envmap.cpp

@@ -109,7 +109,7 @@ class EnvironmentMapEmitter final : public Emitter<Float, Spectrum> {
                 }
 
                 *lum_ptr++ = lum * sin_theta;
-                store(ptr, coeff);
+                store_unaligned(ptr, coeff);
                 ptr += 4;
             }
         }