Fix FORTIFY_SOURCE false positive

Fix FORTIFY_SOURCE false positive

When -D_FORTIFY_SOURCE=2 was given during compilation,
sprintf and similar functions will check if their
first argument is in read-only memory and exit with
*** %n in writable segment detected ***
otherwise. To check if the memory is read-only, glibc
reads frpm the file "/proc/self/maps". If opening this
file fails due to too many open files (EMFILE), glibc
will now ignore this error.

Fixes [BZ #30932]

Signed-off-by: Volker Weißmann <volker.weissmann@gmx.de>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>