libical: global-buffer-overflow in icaltime_timegm

With the following new fuzz target: include include include include include "/src/libical/src/libical/icalcomponent.h" extern "C" int LLVMFuzzerTestOneInputconst uint8t data, sizet size char icalstring = char mallocsize + 1; memcpyicalstring, data, size; icalstringsize = '\0'; icalcomponent comp ...