Close-on-exec flag few missed places

It looks like when scanning for file-descriptor-opening functions for !3283 (merged) I missed a few places:

• One case of fopen () call which was written as fopen() (without space before the opening parenthesis). Rescanned Glib code after this for another function calls written this way, found none relevant.

• Went thorough glibc man pages and Linux man-pages looking for other functions that mention the close-on-exec flag. Within this set of file-descriptor-opening functions, I've spotted calls to setmntent () and mkstemp ()-like family of functions in Glib.

Sorry for missing these cases for the previous MR a few days ago.