Add lstat() error handling not only for ENOENT case.
Otherwise uninitialised 'struct stat st' variable is used later in case of
lstat() non-ENOENT failure which leads to processing of rubbish values of
file mode ('S_ISLNK(st.st_mode)' check) or size ('xsize_t(st.st_size)').
Signed-off-by: Andrey Okoshkin <a.okoshkin@samsung.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>