Fix shader syntax error

data/debayer.frag

@@ -62,13 +62,13 @@ main()
         // should be an uniform
         vec3 corrected = color - 0.02;
 
-#ifdef COLORSPACE_RAW
+#if defined(COLORSPACE_RAW)
         // Fast SRGB estimate. See https://mimosa-pudica.net/fast-gamma/
         vec3 srgb_color =
                 (vec3(1.138) * inversesqrt(corrected) - vec3(0.138)) * corrected;
 
         gl_FragColor = vec4(srgb_color, 1);
-#elif COLORSPACE_SRGB
+#elif defined(COLORSPACE_SRGB)
         gl_FragColor = vec4(color, 1);
 #endif
 }