REDHAT-BUG-2492255: Medium severity GLib vulnerability

A heap-buffer-overflow READ of 1 byte occurs in gkeyfilegetlocalestringlist() at gkeyfile.c:2464 when the resolved locale string value is an empty string (""). The function computes len = strlen(value) which yields 0, then accesses value[len - 1]. Since len is gsize(unsigned), len - 1 wraps to SIZEMAX, causing a read of 1 byte before the heap allocation (under-read). Any application that loads a key file from untrusted input and calls gkeyfilegetlocalestringlist() on a key whose value is empty is affected. The key file format is commonly used for .desktop files and application configuration.