[devel] Bump to version 1.5.0beta50

pngtest.c

@@ -1726,4 +1726,4 @@ main(int argc, char *argv[])
 }
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef version_1_5_0beta49 your_png_h_is_not_version_1_5_0beta49;
+typedef version_1_5_0beta50 your_png_h_is_not_version_1_5_0beta50;